LIBRARY 

OF  THE 

UNIVERSITY*  OF  CALIFORNIA. 

Class 


Corrosion  of  Iron  and  Steel 


Published   by  the 

Me  G  raw  -  Hill   B ook.  Comp  any 

New  York 


.  *Ke5ookDepartraenta  of  the 

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rtTHIItlItIg¥IgI™»JtI«TTITIIglT»rr¥glf¥rrri-mj 


The  Corrosion  of 
Iron  and  Steel 


By 
Alfred  Sang 


NEW  YORK 
McGRAW-HILL  BOOK  COMPANY 

239  West  Thirty-Ninth  Street 
1910 


Copyrighted,  1910 

by  the 

McGRAW-HILL  BOOK  COMPANY 
New  York 


PREFACE 

The  corrosion  of  iron  and  steel  is  one  of  the 
leading  questions  of  the  day  among  engineers, 
metallurgists  and  manufacturers.  Information 
on  the  subject  is  widely  scattered  and  its  value  is 
thereby  greatly  reduced. 

This  essay  is  based  on  a  paper  read  before  the 
Engineers'  Society  of  Western  Pennsylvania,  at 
Pittsburgh,  December  15,  1908,  and  published  in 
the  Proceedings. 

The  work  is  in  great  measure  a  compilation  and 
study  of  the  results  obtained  by  other  investi- 
gators and  is  intended  as  a  compendium  of  the 
subject  suitable  for  reference. 

I  am  indebted  to  Mr.  Harrison  W.  Graver  for 
the  free  use  of  the  extremely  valuable  bibliography 
of  the  subject  published  by  the  Carnegie  Library 
of  Pittsburgh,  which  is  reproduced  in  condensed 
form  at  the  end  of  the  volume. 

ALFRED    SANG 

96  Boulevard  de  Versailles 
Saint  Cloud  (S.  &  O.),  France 
September  6th,  1909 


201345 


CONTENTS. 

Page 

Preface v 

The  Decay  of  Iron 1 

Composition   of    Rust 

Formation  of   Rust 6 

Carbonic    Acid    Theory 9 

Hydrogen   Peroxide  Theory 13 

Electrolytic    Theory 14 

The  Solution  of  Iron  in  Water 22 

Action  of  Hydrogen  and  Occluded  Gases 27 

The   Function  of  Oxygen 36 

The  Difference  between  Iron  and  Steel 38 

The  Structure  of  Iron  and  Steel 40 

Relation  of  Structure  to   Corrosion 42 

Effect  of  Stress  on  Corrosion 45 

Comparative  Corrosion  of  Iron  and  Steel 49 

Influence  of  Modern  Conditions 60 

Corrosion  in  Air 62 

Corrosion  in   Fresh  Water 63 

Corrosion  in  Salt  Water 65 

Corrosion  of  Rails 70 

Corrosion  of  Tubes 73 

Corrosion  of  Wire  and  Sheets 78 

Influence  of  the  Impurities  in  the  Metal 81 

Comparative  Corrosion  of  Acid  and   Basic   Steels.  .    .  87 

Influence  of  the  Electric  Current 88 

Iron  and  Steel  Embedded  in  Concrete 89 

The  Inhibition  of  Rusting 95 

References    102 

General  Bibliography  105 

Authorities   Quoted    .  viii 


Page 

Newberry,  S.  B ,.  91 

Norton,  C.  L 92 

Ostwald  18 

Perry,    J 27 

Phillips,   D 50 

Pittsburgh  Testing  Laboratory 102,  104 

Rasch,  E 46 

Reed,  C  J 104 

Richards  and  Behr 29 

Riverside  Iron  Works 77 

Roberts-Austen,    W 27,  30 

Schumann,    G 103 

Speller,  F.  N 51,  75 

Spring,    W 29 

Stahl,   K.  F 59 

Ste.   Claire-Deville 32 

Steinmetz    30 

Stodart  and  Faraday 22 

Thomson,  T.   N 73 

Thorner     43 

Tilden    3 

Toch,    M 3 

Traube  13 

Troost  and  Hautefeville 30 

Unger,  J.   S 57 

Walker,  W.  H 15,  18,  23,  36,  37,  84 

Ward  and  Bauerman 8 

Whitney,  W.  R 10,  22 

Wiedermann    29 

Winckleman   • 32 

Witkowski,   A 46 

Wood,  M.  P • 2,  86 

x 


OF   THE 

UNIVERSITY 

OF 


The  Corrosion  of  Iron  and  Steel 


THE  DECAY  OF  IRON 

The  decay  of  iron  and  steel  by  corrosion,  if 
natural  agencies  are  allowed  to  act  on  them,  is  far 
more  rapid  than  that  of  wood,  concrete  and  other 
materials  of  construction.  Steel  is  being  used  more 
and  more  every  day  for  buildings  and  other  struct- 
ures, and  on  the  prevention  of  this  decay  depends 
the  permanency  of  these  works  and  the  safety  of 
future  generations.  Were  it  not  for  iron  and  steel, 
the  erection  of  large  works  of  engineering  would 
have  been  impossible,  and  their  very  size  and  con- 
sequent high  cost,  representing  as  it  does  a  large 
sum  of  human  energy — which  is  after  all  the  only 
true  foundation  for  wealth — make  it  a  duty  to  pre- 
serve them  from  decay. 

On  a  structure  like  the  Forth  Bridge,  a  number 
of  men  are  kept  constantly  at  work,  cleaning  rust- 
spots  and  repainting.  The  wise  course  of  preserv- 
ing such  structures  for  the  use  of  our  descendants 
is  not  generally  followed,  and  it  is  only  when  acci- 
dents like  the  one  at  Charing  Cross  Station  in 
London  take  place  that  interest  is  revived  for  a 
time  in  the  question.  Wood,  in  referring  to  the 


2        THE  CORROSION  OF  IRON  AND  STEEL 

roof  of  a  gas-works  in  New  York  City  which  col- 
lapsed for  lack  of  attention,  forecasted  a  similar 
fate  sooner  or  later  for  structures  like  the  viaducts 
of  the  elevated  railway  of  the  same  city,  which 
almost  casual  observation  will  show  are  repainted 
over  the  rust  without  any  preliminary  cleaning. 

On  account  of  this  necessity  of  combating  corro- 
sion, it  is  imperative  that  engineers  arrange  the 
design  so  that  every  part  of  structural  works  be 
readily  accessible  for  frequent  inspection.  It  has 
been  truly  said  that  "wrought  iron  is  not  only  a 
bad  but  a  dangerous  material  if  neglected" ;  this  is 
far  more  true  of  steel,  because,  starting  from  a 
higher  tensile  strength,  it  decays  as  rapidly,  and 
often  more  rapidly,  than  iron,  down  to  the  point  of 
failure. 


COMPOSITION  OF  RUST 

In  order  to  bring  about  improvements  in  the 
protection  of  metals  from  corrosion,  it  is  necessary 
to  study  the  nature  of  this  corrosion;  to  devise 
either  preventives  or  cures  the  disease  itself  must 
be  understood. 

Rust  is  a  ferric  sesquioxide  (Fe2O3nH2O)  which 
may  or  may  not  be  hydrated ;  it  is  of  a  brown,  red- 
brown  or  yellow-brown  color ;  when  formed  under 
water  it  is  generally  of  a  deeper  tint  and  is  of  a 
somewhat  colloidal  nature.  Rust  formed  by  the 
rapid  evaporation  of  water  on  the  surface  of  iron 
is  usually  of  a  Jeep  red-brown  color,  has  a  shiny 
appearance  and  is  high  in  combined  water.  Oxida- 
tion at  a  high  temperature  yields  the  magnetic  oxide, 

Fe:A. 

The  composition  of  rust  varies  within  narrow 
limits;  magnetic  oxide  (Fe,O4)  is  always  present 
(Tilden)  ;  according  to  Toch,  the  rust  nearest  the 
iron  is  highly  ferrous,  blending  outwardly  into  a 
more  stable  oxide;  this  is  due  to  the  progressive 
way  in  which  the  decomposition  takes  place ;  An- 
drews has  shown  that  the  rate  of  decomposition 
also  increases  progressively,  being,  under  the  con- 
ditions of  his  experiments,  about  50  per  cent  more 


4         THE  CORROSION  OF  IRON  AND  STEEL 

rapid  the   second  year  than   the  first.     Rust   also 
contains  some  ferrous  carbonate. 

Moody  gives1  the  following  data  on  the  rust  from 
the  inside  of  some  iron  tanks  which  had  been  in 
constant  use : 

No.    i.       2.         3.         4.         5.         6. 

%     Iron    as    ferric    oxide 55-73  51.12   64.60  65.13  68.89  67.46 

%    Iron   as   ferrous   oxide 32.86  36.57   25.74  25.66  23.18  24.40 

%    Iron   as   ferrous   carbonate..    11.40  12.31     9.66      9.21     7.93     8.14 

Rust  from  lot  No.  i  was  crushed  and  exposed 
to  the  air  during  eight  days,  resulting  in  a  great 
increase  of  the  more  stable  ferric  oxide  (Fe2O3), 
the  ferrous  oxide  (FeO)  falling-  to  14.11%  and  the 
ferrous  carbonate  (FeCO.3)  to  5.62%. 

Recent  analyses*  of  rusts  formed  by  the  total 
decomposition  in  the  open  air  under  normal  con- 
ditions of  a  mild  steel  rivet  rod,  a  light  steel  rail,  a 
steel  sheet  as  used  for  roofing  and  an  iron  chain 
link,  gave  the  following  results,  the  FeO  and  CCX 
being  corrected  to  magnetic  oxide  and  carbonate, 
respectivelv : 

Rod.    Rail.  Sheet.  Chain. 

Free     Moisture .12       .11  .24       .08% 

Ferric    Oxide     (FeoO3) 85.41   84.92  80.9680.55 

Magnetic    Oxide    (FesO,) 541      1.77  4.41   20.66 

Ferrous   Carbonate    (FeCO.O    .84      2.24  .95       .81 

Manganese  Dioxide  (MnOa) .41        .73  .54       .06 

Carbon    &    carbonaceous    matter....  .15        .93  1.17        .20 

Combined     water 5.90     6.60  9.42     3.88 

Silica    and    Insoluble    matter .14        .05  1.50      1.44 

Undetermined      1.74     2.76  1.05     2.94 

It  will  be  noticed  that  in  all  cases  the  amount  of 
magnetic  oxide  is  in  inverse  ratio  to  the  manganese 
content.  The  magnetic  oxide  in  the  rail  and  sheet 
rusts  is  evidently  due  to  the  original  mill-scale,  but 
in  the  rod,  which  had  remained  exposed  during  over 

*  Made  for  the  author  by  Mr.  J.  J.  Miller. 


COMPOSITION  OF  RUST  5 

four  years,  it  is  much  higher;  the  very  high  per- 
centage in  the  chain  which  had  been  corroding 
during  15  years  or  more  in  the  mud  of  the  Panama 
Canal  -zone'1'  may  bear  some  relation  to  the  fact  that 
after  being  brought  into  the  air  in  an  apparently 
sound  condition  it  rapidly  disintegrated,  probably 
owing  to  the  rapid  oxidation  of  unstable  ferrous 
oxide  (FeO)  or  its  combination  with  Fe,O,  to 
form  Fe3O4. 

Rust  is  not  crystalline;  it  is  granular  and  amor- 
phous; very  ancient  rust  is,  however,  said  to  con- 
sist of  a  mixture  of  magnetic  oxide  and  anhydrous 
sesquioxide  in  a  more  or  less  crystallized  condition, 
not  unlike  the  crystalline  hematite,  or  oligistic  iron, 
abundant  in  Elba,  but  also  found  in  other  iron-ore 
regions.  The  higher  proportion  of  Fe.,O4  and  low 
proportion  of  combined  water  in  the  chain  rust 
from  Panama  would  appear  to  confirm  this.  It  is 
also  claimed  that  ammonia  may  be  formed  during 
rusting,  as  in  the  case  of  organic  matter  under- 
going decomposition ;  Bloxam  and  others  claim  that 
ammonia  is  formed  from  the  nitrogen  of  the  air 
during  the  process  of  rusting. 


*  This  chain  link  was  supplied  by  Mr.   A.   E.  Crockett,  Gen.  Mgr. 
of  the   Standard  Chain  Co. 


FORMATION  OF  RUST 

Under  ordinary  conditions,  corrosion  never  seems 
to  take  place  evenly ;  upon  closer  investigation  it  is 
found  that  it  does  not  and  cannot  take  place  evenly ; 
this  is  due  to  "pitting."  The  rust  commences  to 
form  at  distinct  points  which  must  therefore  be 
particularly  liable  to  attack;  the  spreading  of  the 
rust  from  these  original  points  is  like  that  of  a 
disease.  There  is  a  peculiar  formation  known  as 
"tubercular  corrosion''  which  owes  its  name  to  the 
wart-like  concretions  of  rust  and  earthy  matter  de- 
rived from  the  water,  which  grow  on  the  metal ; 
this  form  of  corrosion  is  specially  frequent  in  cases 
where  alkalies  and  saline  matter  are  present  to- 
gether in  a  highly  aerated  water;  it  is  common  in 
water-mains.  If  the  ''tubercle"  is  removed,  a  hole 
is  found  in  its  place. 

Rusting  starts  at  certain  points  and  spreads  out 
until  the  different  growths  unite  into  a  continuous 
covering.  The  theory  of  pitting,  due  to  John,  is 
that  at  the  point  where  it  takes  place  there  is  a 
speck  of  impurity,  such  as  a  particle  of  slag  or 
scale,  or  a  segregated  constituent  of  the  metal,  which 
gives  rise  to  galvanic  action. 

6 


FORMATION  OF  RUST  7 

Where  pitting  is  serious,  corrosion  may  reach 
through  a  plate  long  before  the  greater  part  of  the 
surrounding  surface  is  seriously  rusted.  Were  cor- 
rosion to  take  place  evenly,  the  life  of  the  material 
would  be  greatly  extended.  In  proof  of  this  Mallet 
made  a  series  of  experiments-;  they  were  carried 
out  on  large  surfaces  and  at  ordinary  temperatures 
over  a  long  period  of  time ;  he  found  the  following 
average  relative  depths  of  corrosion,  corrected 
for  one  century  of  time,  for  steel  and  wrought  iron 
taken  together: 

In     the    atmosphere    and    freely    exposed    to    the 

weather      0.0343  °f  an  inch 

In  fresh   river  water 0.0352  " 

In  clear  open   sea-water 0.3263  " 

In     sewage-fouled    sea-water 0.5327  "     "     " 

The  tables  of  actual  results  with  various  grades 
of  iron  and  steel  which  yielded  the  above  averages 
are  very  instructive,  although  the  chemical  com- 
positions and  physical  conditions  must  in  many,  if 
not  all,  cases  have  differed  from  those  of  equivalent 
qualities  manufactured  nowadays. 

As  seasons  and  conditions  recur,  rust  forms  in 
layers  which  can  be  detached  from  each  other. 
Being  more  or  less  spongy  and  perhaps  hygroscopic, 
it  will  retain  moisture  in  close  proximity  to  the 
iron,  besides  giving  rise  to  an  unfavorable  voltaic 
action.  Prof.  W.  H.  Gee  states3  that  a  bright  steel 
in  contact  with  the  same  steel  after  rusting  24 
hours  in  the  atmosphere  of  Manchester,  showed  a 
difference  of  potential  of  0.104  v-  Rust  in  contact 
with  iron  hastens  its  corrosion  by  acting,  there- 
fore, as  a  depolarizer;  it  is  very  voluminous  and 


8         THE  CORROSION  OF  IRON  AND  STEEL 

may  occupy  as  much  as  ten  times  the  space  of  the 
original  iron  (Ward  and  Bauerman).  It  may  also 
act  as  a  carrier  for  oxygen,  furnishing  it  to  the 
iron  and  replacing  it  from  the  air.  These  prop- 
erties promote  the  growth  of  rust  both  laterally  and 
in  depth. 

Rusting  is  the  reverse  of  the  process  of  iron 
smelting;  the  corrosion  of  iron  to  the  sesquioxide 
must  release  the  same  number  of  calories  as  would 
be  absorbed  in  converting  a  natural  sesquioxide  into 
iron. 

As  will  be  seen  presently,  while  there  is  con- 
siderable doubt  as  to  the  necessity  of  an  acid  being 
present  to  cause  rusting,  there  is  no  doubt  whatever 
about  the  necessity  that  both  oxygen  and  water 
be  present;  it  is  generally  agreed  that  the  moisture 
must  be  able  to  condense  on  the  surface  of  the 
metal.  This  is  by  no  means  proven,  although 
theoretical  considerations  require  that  the  water  be 
in  the  liquid  form. 

There  are  three  theories  of  rusting,  and  in  exam- 
ining them  it  is  well  to  bear  in  mind  that,  while 
one  or  other  of  them  may  explain  the  true  first 
cause  of  rusting,  the  others  may,  and  some  of  them 
undoubtedly  do,  present  conditions  which,  if  not 
essential,  at  least  intensify  the  decomposition. 
A  summary  of  theories  has  been  published  by 
Mugdan.4 


CARBONIC  ACID  THEORY 

The  oldest  of  .the  plausible  theories  of  corrosion, 
whose  chief  supporters  have  been  Dr.  F.  Grace 
Calvert5  and  Prof.  Gerald  T.  Moody,6  supposes  that 
carbonic  acid  attacks  the  iron,  converting  it  into 
a  carbonate  and  releasing  hydrogen,  which  unites 
with  the  oxygen  present,  as  air  or  otherwise,  to 
decompose  the  ferrous  carbonate  to  ferric  hy- 
droxide, or  rust,  leaving  the  same  amount  of  acid 
as  was  originally  present  to  react  as  before  and 
form  more  rust. 

The  nature  of  the  reaction  may  be  described  as 
follows : 

2Fe  +  2CO2  +  2H2O  =  2FeCO,  +  4H 
4H  +  2FeCO,  +  30  =  Fe2O3  +  2CO2  +  2H2O. 

The  carbonic  acid  may  be  written  H2CO,  and  the 
residual  2H.2O  may  be  applied  to  the  hydration  of 
Fe2O3  and  CO2. 

The  theory  is  a  logical  one.  The  objection  that 
it  is  not  proved  that  iron  will  not  rust  in  thoroughly 
boiled  distilled  water  is  not  insuperable.  Stephane 
Leduc  has  shown  that  it  is  impossible  to  extract 
all  of  the  dissolved  gases  from  distilled  water  by 
boiling ;  he  claims  that  not  less  than  one  cubic 
centimeter  of  gas  would  be  left  in  one  liter  of 

9 


10      THE  CORROSION  OF  IRON  AND  STEEL 

water,  which  it  is  impossible  to  remove.  Part  of 
this  gas  must,  almost  certainly,  be  carbonic  dioxide, 
of  which  there  is  0.04  per  cent  present  in  the  atmos- 
phere ;  it  is  more  soluble  in  wrater  than  the  oxygen 
and  nitrogen  of  the  air. 

The  operation  of  rusting  being,  according  to  this 
theory,  a  cyclical  or  regenerative  one,  it  has  been 
argued  (Whitney)  that  a  single  molecule  of  car- 
bonic dioxide  would  be  sufficient  to  start  and  main- 
tain corrosion  in  the  presence  of  air  and  water. 
The  carbonic  acid,  due  to  the  reaction  of  the  car- 
bonic dioxide  with  water,  would  help  iron  into 
solution;  this  is  all  that  is  necessary  to  corrosion, 
the  dissociated  iron  or,  more  likely,  the  ferrous 
carbonate  being  oxidized  to  rust  in  the  presence  of 
oxygen.  If,  however,  this  residual  gas  in  water 
cannot  be  removed  by  physical  means,  such  as  boil- 
ing, it  might  be  feasible  to  do  so  chemically ;  this 
may  be  the  case  with  oxidizing  agents  used  as  rust 
inhibitors,  to  be  referred  to  later;  even  then  it  is 
possible  that  a  definite  degree  of  concentration  of 
the  acid  neutralizer  would  have  to  exist,  as  the 
rusting  of  iron  in  weak  alkaline  solutions  would 
seem  to  indicate. 

Prof.  A.  Crum  Brown  has  described,  as  follows, 
the  rusting  of  iron  by  a  drop  of  water  in  the 
presence  of  CO«  :7  "At  first,  for  a  short  time,  the 
drop  remains  clear,  and  the  bright  surface  of  the 
iron  is  seen  through  it;  but  soon  a  greenish  pre- 
cipitate forms  in  the  drop,  and  this  rapidly  becomes 
reddish  brown.  This  brown  precipitate  does  not 


CARBONIC  ACID  THEORY  11 

adhere  to  the  iron,  but  is  suspended  in  the  water 
and  becomes  a  loosely  adherent  coating  only  when 
the  water  has  evaporated." 

The'  careful  investigations  of  Dr.  A.  S.  Cushman* 
and  others  seem  to  show,  almost  conclusively,  that 
rusting  will  take  place  when  there  is  no  carbonic 
acid  present ;  when  there  is,  a  greenish  carbonate 
is  formed,  which  promptly  changes  to  the  hydroxide 
when  oxygen  is  supplied  to  it.  While  the  carbonic 
acid  theory  may  accurately  describe  how  rusting 
does  actually  take  place  under  normal  conditions, 
and  be,  therefore,  correct,  there  seems  to  be  little 
reason  to  doubt  but  that  rusting  can  take  place 
without  its  aid.  This  conclusion,  based  on  the 
valuable  work  of  Cushman  and  Walker,  agrees 
with  what  Mallet  wrote  in  1872:  "If  the  air  con- 
tains vapour  of  water,  however,  chemical  action 
rapidly  occurs,  more  rapidly  if  carbonic  acid  also 
be  present.  The  presence  of  the  latter  is,  however, 
not  necessary  to  initiate  the  action,  as  has  been 
stated  by  Calvert." 

Carbonic  acid  will  greatly  increase  the  rate  of 
corrosion.  The  following  figures,  giving  the  loss 
in  milligrams  per  square  inch  of  surface  for  two 
grades  of  iron  of  exceptional  purity  and  two  steels 
of  ordinary  quality,  are  typical  :9 

5    Hrs.    in                 Aerated    Water.     Aerated   Water  Increased    loss 

and  CO2  due  to  CO2. 

Iron    No.     i 2.70                          4.45  66% 

Iron     No.    2 2.60                           4.42  70% 

O.    H.    Steel 3.17                          5.25  66% 

Steel    Nipple    3.76                          5.32  42% 

Prof.  Moody  to  show  the  importance  of  the 
action  of  CCX  gives  the  following  figures10  showing 


12       THE  CORROSION  OF  IRON  AND  STEEL 

the  percentage  of  the  total  oxygen  in   100  c.c.  of 
air  which  were  taken  up  by  10  grams  of  iron  : 

Ord.    Air  and  Air    and    water; 

dist.  water.  almost  entirely 

freed  from  COo. 

After           6  Hrs 5.7  None 

24     '       29.  i  None 

72     "      61.3  0.9 

1 68     '       94-3  3-8 

The  conclusions  of  E.  lleyn  and  O.  Bauer  con- 
cerning the  effect  of  CO2  in  rusting,  derived  from 
their  recent  researches,11  are  as  follows:  i.  Iron 
will  rust  under  conditions  in  which  CO2  is  abso- 
lutely absent.  2.  Air  containing  15%  of  CO2  under 
the  same  conditions  is  only  twice  as  active  as  air 
absolutely  free  from  CCX.  It  is  not  likely  or  pos- 
sible that  the  small  amount  present  in  the  atmos- 
phere exerts  any  action  on  the  process  of  rusting. 
3.  Pure  CO2  causes  no  peculiar  rusting.  It  acts  as 
any  acid  by  dissolving  with  the  evolution  of 
hydrogen. 


HYDROGEN  PEROXIDE  THEORY. 

The  second  theory  of  rusting-,  originally  due  to 
Traube,12  is  known  as  the  peroxide  theory.  Accord- 
ing to  this  theory,  the  iron,  oxygen  and  water  are 
supposed  to  react  to  form  ferrous  oxide  (FeO)  and 
hydrogen  peroxide  (H2O2),  which  then  unite  to 
form  the  ferric  hydroxide,  leaving  an  excess  of 
hydrogen  peroxide  which  attacks  a  new  quantity 
of  iron. .  The  reaction  might  be  somewhat  as  fol- 
lows : 

2Fe  +  2H2O  +  40  =  2FeO  +  2H2O2  = 
Fe2O3  +  H2O,  +  H2O. 

While  it  is  true  that  iron  immersed  in  commer- 
cial peroxide  shows  a  red  precipitate  of  rust,  it  has 
been  found  impossible  to  detect  the  presence  of 
hydrogen  peroxide  during  ordinary  rusting,  and 
while  this  failure  may  not  condemn  the  theory,  it 
makes  it  appear  improbable.  Both  Moody  and 
Cushman  claim  that  iron  does  not  rust  in  pure 
neutral  hydrogen  peroxide. 


ELECTROLYTIC  THEORY 

The  third  and  most  widely  accepted  theory  is  the 
electrolytic  one. 

When  two  substances  of  different  polarity  are 
immersed  in  a  suitable  electrolyte — or  medium  con- 
taining free  ions  of  matter — an  electric  current  is 
set  up,  and  the  substance  from  which  the  current 
flows  tends  to  dissolve.  Whether  or  not  this  "gal- 
vanic solubility"  explains  all  solubilities,  or,  as  gen- 
erally believed,  pure  metals  have  a  solution  tension 
similar  to  the  diffusion  of  gases,  is  a  matter  for 
investigation.  So  far  as  corrosion  is  concerned,  the 
electrolytic  theory  implies  the  solution  of  the  iron 
in  water  or  moisture  as  ferrous  ions ;  the  iron,  while 
in  this  dissociated  condition,  is  oxidized  by  any  free 
oxygen  present.  To  quote  Dr.  Cushman  :13  "If, 
therefore,  we  immerse  a  strip  of  iron  in  a  solution 
containing  hydrogen  ions  iron  \vill  go  into  solution, 
and  hydrogen  will  pass  from  the  electrically  charged 
or  ionic  to  the  atomic  or  gaseous  condition.  In  such 
a  system  the  solution  of  the  iron  and,  therefore, 
its  subsequent  oxidation,  must  be  accompanied  by 
a  'precipitation/  or  setting  free  of  hydrogen.  It  is 
very  well  known  that  solutions  of  ferrous  salts  as 
well  as  freshly  precipitated  ferrous  hydroxide  are 

14 


ELECTROLYTIC  THEORY  15 

rapidly  oxidized  by  the  free  oxygen  of  the  air  to  the 
ferric  condition,  so  that  if  the  electrolytic  theory 
can  account  for  the  original  solution  of  the  iron  the 
explanation  of  rusting  becomes  an  exceedingly 
simple  one." 

Thus,  Dr.  Cushman  explains — and  in  this  he  is 
in  agreement  with  Dr.  Walker — that  hydrogen  ions 
must  be  present,  either  from  dissociation  of  the 
water  or  otherwise,  before  solution  can  take  place. 
The  natural  tendency  of  the  metal  to  dissolve  puts 
ions  of  iron  into  solution,  and,  in  order  to  restore 
electrostatic  equilibrium,  the«  hydrogen  is  precipi- 
tated in  a  gaseous  condition.  It  is  extremely  doubt- 
ful as  to  there  being  any  hydrogen  actually  pre- 
cipitated in  ordinary  corrosion ;  there  would  usually 
be  sufficient  dissolved  oxygen  present  to  oxidize 
the  nascent  hydrogen.  It  is  commonly  taken  for 
granted  that  there  is  always  a  certain  degree  of 
dissociation  in  water,  but  this  remains  as  yet  un- 
proven ;  in  ordinary  water  it  may  well  be  the  case 
on  account  of  the  presence  of  impurities. 

The  process  of  rusting,  stated  in  Dr.  Walker's 
words,  is  as  follows:14  ''When  a  metal  is  placed 
in  water  or  in  an  atmosphere  sufficiently  moist  so 
that  a  film  of  water  condenses  on  its  surface,  the 
action  which  may  take  place  is  essentially  one  of 
solution.  Every  metal  has  a  tendency  to  pass  into 
water  solution  in  the  ionic  form,  assuming  a  posi- 
tive charge  of  electricity  and  leaving  the  metal  nega- 
tively charged.  To  maintain  electrostatic  equilib- 
rium, an  equivalent  amount  of  positive  electricity 


16       THE  CORROSION  OF  IRON  AND  STEEL 

must  leave  the  solution  by  the  separation  of  hydro- 
gen ions  from  the  dissociated  water  in  the  form  of 
hydrogen  gas,  charging  that  portion  of  the  metal 
on  which  the  hydrogen  separates  positively,  and 
leaving  the  solution  negatively  charged.  An  elec- 
trolytic current  is  thus  produced  which  is  carried 
from  one  point  on  the  iron  to  the  solution  by  the 
escaping  iron  ions,  and  from  the  solution  again  to 
the  iron  by  the  separating  hydrogen  ions,  and 
equilibrium  again  restored.  The  speed  of  this  reac- 
tion depends,  first,  upon  the  escaping  tendency  of 
the  metal  itself,  measured  by  its  solution  pressure; 
second,  upon  the  concentration  of  the  hydrogen 
ions,  increasing  as  this  concentration  is  increased ; 
third,  upon  the  ease  with  which  deposited  hydrogen 
ions  can  assume  a  gaseous  state  and  escape  or  be 
removed  from  the  metallic  surface." 

The  second  and  third  points  relating  to  hydrogen 
will  receive  further  attention  in  a  subsequent  sec- 
tion. As  regards  the  assumption  that  "every  metal 
has  a  tendency  to  pass  into  water  solution  in  the 
ionic  form,"  it  is  worth  pointing  to  the  well- 
established  fact  that  solution-tension  varies  more 
or  less  as  the  polarity;  metals  which  are  negative 
to  hydrogen,  all  conditions  being  equal,  are  en- 
dowed with  less  "solution  pressure"  than  those 
which  are  positive  to  it.  It  is  justifiable  to  claim 
relationship  between  these  two  properties. 

It  is  erroneous  to  say  that  iron  only  corrodes 
when  anode.  Ordinary  iron  corrodes,  whatever  the 
galvanic  position  of  the  mass  may  be  in  reference 


ELECTROLYTIC  THEORY  17 

to  its  surroundings ;  as  will  appear  later,  all  that  is 
necessary  besides  the  electrolyte  to  cause  corrosion 
is  a  few  voltaic  couples  in  the  mass,  or  else,  as  just 
stated,-  free  dissociated  hydrogen  in  contact.  Iron 
as  cathode  is  less  liable  to  corrosion,  and  this  fact 
is  taken  advantage  of  in  engineering  work,  to  in- 
hibit rusting. 

The  electrical  inoxidation  process  of  de  Meritens15 
seems  to  be  a  reproduction  on  a  rapid  scale  of  the 
process  of  electrolytic  corrosion.  Iron  containing 
occluded,  and  therefore  presumably  dissociated,  hy- 
drogen, and  immersed  in  warm  distilled  water,  is 
rusted  by  connecting  it  to  the  positive  pole  of  a 
battery  supplying  a  current  of  low  voltage;  if  the 
current  is  as  weak  as  can  be  made  to  pass  through 
the  water,  the  formation  is  one  of  black  oxide,  or 
the  rust  is  converted  into  black  oxide.  If  the 
iron  is  free  from  hydrogen  it  is  necessary  to  first 
connect  it  to  the  negative  pole  so  that  it  may  absorb 
some,  else  the  action  will  not  take  place.  The  part 
played  by  hydrogen  in  this  process  is  most  interest- 
ing and  bears  out  the  statement  of  Dr.  Cushman 
which  has  been  quoted,  giving  it,  however,  more 
exact  significance ;  it  would  seem  that  the  hydrogen 
ions  may  be  dispensed  with  in  the  solution  if  they 
are  occluded  in  the  iron.  Hydrogen  is  not  merely 
a  by-product  in  the  process  of  rusting ;  it  seems  to 
play  an  essential  part  as  an  "exciter"  in  "setting-ofF' 
the  reaction,  by  creating  a  galvanic  current.  Free 
hydrogen  ions  are  known  to  be  extremely  active 
catayltic  agents :  we  will  return  to  this  subject  later. 


18        THE  CORROSION  OF  IRON  AND  STEEL 

The  action  taking  place  in  corrosion  by  electroly- 
sis may  be  written  as  follows  : 


Fe  )          (  Fe  (ion)      } 

Impurity  [  =  •]        or  \ 

H2O         )          (Imp.  (ion)J 


+  H  (ion)  +  HO 


-  +HO-H2  (mol.)  +  FeO 
2FeO+O=Fe2O5 

HO  is  decomposed  at  the  negative  pole  and  hy- 
drogen is  precipitated;  FeO  is  oxidized  at  the 
positive  pole  to  form  rust. 

In  the  above  formula  the  solution  of  the  iron  is 
shown  as  being  due  either  to  the  action  of  impuri- 
ties in  contact  with  it,  intensified  by  the  contact- 
effect  of  the  nascent  hydrogen  given  off,  or  else 
entirely  to  the  action  of  the  hydrogen  when  the 
impurities  are  positive  to  the  iron.  If  the  im- 
purities are  positive,  the  hydrogen  is  given  off  at 
the  surface  of  the  iron  and,  as  Dr.  Walker  says, 
charges  the  solution  negatively.  The  fact  of  a 
metal  being  positive  to  an  electrolyte  in  which  it 
is  immersed  is  the  cause  of  its  electrolytic  (gal- 
vanic) solution,  in  accordance  with  Ostwald's 
Table,  and  solution  will  proceed  until  the  negative 
charges  carried  by  the  ions  of  the  metal  into  the 
electrolyte  have  accumulated  to  the  point  of  coun- 
terbalancing the  positive  charges  on  the  surface  of 
the  metal.  This  counter-potential  is,  necessarily,  pro- 
portional to  the  osmotic  pressure,  both  depending 
on  the  concentration  of  the  ions  in  solution. 

That  the  operation  of  rusting  is  of  an  electrolytic 
nature  was  very  beautifully  shown  in  the  experi- 


ELECTROLYTIC  THEORY  19 

ments  suggested  by  Dr.  W.  H.  Walker  and  carried 
out  by  him  in  collaboration  with  Dr.  Cushman.16 
A  "feroxyP  reagent  was  prepared  by  neutralizing  a 
hot  solution  of  gelatine  with  i/ioo  normal  potas- 
sium hydroxide,  using  phenolphthalein  as  indi- 
cator, after  which  a  few  drops  of  a  dilute  solution 
of  potassium  ferricyanide  were  added.  The  pieces 
to  be  tested  were  immersed  in  this  preparation, 
which  solidified  on  cooling,  incasing  them;  diffu- 
sion being  retarded  by  the  colloidal  nature  of  the 
medium,  local  discolorations  were  expected  to  in- 
dicate the  progress  of  chemical  action.  In  these 
experiments  the  development  of  hydroxyl  (HO) 
ions  at  the  negative  poles  was  shown  by  a  pink 
coloration  due  to  organic  anions  from  the  phenol- 
phthalein, and  at  the  positive  poles  the  solution  of 
the  iron  was  shown  by  the  blue  coloration  due  to  the 
ferrous  cations. 

In  these  tests  it  was  found  that,  as  a  rule,  the 
ends  of  the  test-pieces  were  positive,  giving  rise  to 
a  blue  coloration  indicating  ferrous  ions,  and  rust 
was  formed;  at  the  central  part  where  the  pink 
coloration  developed,  the  ions  remained  bright. 
The  photographs  published  show  nails  which  have 
their  positive  poles  situated  at  the  head  and  in  most 
cases  at  the  point  also;  this  suggests  that  the 
compression  of  the  head  by  upsetting  and  the 
squeezing  of  the  end  between  the  cut-off  dies  when 
the  point  is  formed,  resulting  in  an  overstrained 
(crystallized)  condition  of  these  parts,  may  ac- 
count for  their  positive  polarity.  After  a  while 


20      THE  CORROSION  OF  IRON  AND  STEEL 

there  would  take  place  a  complete  reversal,  the 
positive  and  negative  poles  changing  places  until  a 
further  reversal  brought  back  the  original  condi- 
tions, and  so  on  continuously ;  in  this  way  the  dif- 
ferent parts  of  the  test-pieces  rusted  alternately. 

The  change  of  polarity  is  no  doubt  due  to  the 
formation  of  rust  which  would  in  time  change  the 
potential  of  the  positive  nodes  in  relation  to  the 
negative  nodes.  That  after  the  first  reversal  a 
balanced  system  is  not  reached  when  there  is  an 
even  coating — as  far  as  the  eye  can  judge — all  over 
the  pieces,  might  be  due  to  an  effect  of  persistence, 
similar  to  hysteresis,  which  would  carry  the  action 
over  the  neutral  point,  as  a  fly-wheel  carries  an 
engine  over  the  dead-center,  but  is  more  likely  due 
to  the  very  fact  that  rusting  starting  at  separate 
points,  there  can  be  no  coating  really  even  in  depth. 
Iron  never  becomes  passive  through  rusting. 

Dr.  Cushman  gives  an  excellent  discussion  of  the 
relation  of  this  electrolytic  theory  to  the  rusting  of 
iron.16  He  shows  that  if  a  piece  of  iron  or  steel  is 
immersed  in  water,  positive  and  negative  spots  are 
established;  according  to  his  theory  iron  passes 
into  solution  at  the  positive  spots  and  is  converted 
into  hydroxide,  part  of  which  piles  up  around  those 
spots  in  crater-like  formations,  the  rest  migrating 
to  the  negative  spots,  where  it  collects  in  the  form 
of  cones.  Microscopical  examination  readily  veri- 
fies the  presence  of  these  craters  and  cones ;  we 
have  here  a  plausible  description  of  "pitting"  which, 
whether  on  a  small  or  large  scale,  always  initiates 


ELECTROLYTIC  THEORY  21 

the  process  of  rusting.  Rust  cannot  take  place 
unless  negative  and  positive  spots  are  established, 
the  latter  rusting  first  and  continuing  to  do  so 
until  their  polarity  has  changed;  so  much  seems  to 
he  proven ;  hence  homogeneity  is  the  best  insurance 
against  corrosion;  a  speck  of  impurity  will  give 
rise  to  a  positive  annulus  if  it  is  negative  to  the 
iron  surrounding  it,  and  the  iron  will  go  into  solu- 
tion. 


THE  SOLUTION  OF  IRON  IN  WATER 

In  1822,  Stodart  and  Faraday  showed17  that  vol- 
taic couples  being  present  throughout  the  mass  of 
commercial  metals  are  the  cause  of  these  impure 
metals  being  dissolved  more  rapidly  by  acids  than 
those  which  are  of  purer  composition. 

The  resistivity  of  metals  to  acids  is  not,  however, 
always  an  indication  of  the  degree  of  resistance  to 
corrosion.  With  a  solution  so  weak  that  the  action 
is  no  faster  than  in  ordinary  corrosion  under  severe 
natural  conditions,  the  rates  are  probably  about  the 
same.  To  secure  reliable  data  from  acid  tests,  it 
is  necessary  to  work  with  extremely  dilute  solutions, 
not  exceeding  i  gram  of  acid  per  liter  of  water; 
the  action  is  then  too  slow  to  be  of  practical  service 
as  a  rapid  test  for  corrodibility.  In  a  later  section 
some  interesting  tests  by  Gruner  will  be  introduced. 

The  actual  solution  of  iron  by  water,  whether 
brought  about  by  the  voltaic  effect  of  the  contact 
between  the  metal  and  its  impurities  or  by  any  other 
cause,  is  the  crucial  point  of  the  electrolytic  theory 
of  corrosion.  Whitney  seemed  to  have  proved  be- 
yond a  doubt  that  iron  is  soluble  in  water,18  and  his 
results  were  confirmed  by  Miss  Cedarholm  and 
Bent,  yet  Dunstan  and  others  failed  to  obtain  any 


THE  SOLUTION  OF  IRON  IN  WATER          23 

solution  whatever  under  apparently  identical  con- 
ditions; they  therefore  rejected  the  theories  that 
hydrogen  is  evolved  during  rusting  and  that  iron 
dissolves  in  pure  water.  Dr.  Walker  supported 
Whitney's  theory  of  the  solution  of  iron  as  positive 
ions;  under  the  same  conditions,  in  distilled  water, 
it  is  asserted,  that  lead  also  will  go  into  solution.19 

To  help  solve  the  problem,  Dr.  Cushman  devised 
a  simple  method20  for  testing  iron  and  steel  samples 
in  water  free  from  air  and  carbonic  acid.  In  every 
case  the  metal  remained  bright,  but  rusted  as  soon 
as  the  air  was  admitted.  To  find  out  if  iron  did 
actually  go  into  solution  before  the  admission  of  the 
gases,  a  small  amount  of  phenolphthalein  was 
added;  sooner  or  later  it  showed  the  presence  of 
iron  by  its  pink  color.  The  smallest  amount  of 
iron  which  could  be  detected  in  this  way  would  be 
.0004  gram,  and  it  was  claimed  that  the  indicator, 
although  itself  a  weak  acid,  could  not  account  for 
the  solution  of  the  iron.  If  uniform  confirmations 
of  these  results  are  forthcoming  from  equally  re- 
liable sources,  the  electrolytic  theory  of  corrosion 
is  proven,  at  least  for  ordinary  iron,  because  in  all 
these  tests,  while  taking  into  account  the  composition 
of  the  medium,  the  experimenters  apparently  fail 
to  take  into  account  the  minute  variations  which 
must  have  existed  between  the  various  so-called 
pure  irons  used.  It  may  well  be  doubted  if  theo- 
retically pure  iron  would  dissolve  in  theoretically 
pure  water,  in  which  case  the  solution  of  iron,  as 
observed  by  Cushman,  would  be  due  to  the  galvanic 


24      THE  CORROSION  OF  IRON  AND  STEEL 

action  between  the  iron  and  its  impurities,  causing 
electrolysis  of  water,  the  hydrogen  liberated  then 
forming  a  couple  with  the  iron,  the  latter  being  the 
positive  and  soluble  partner.  Dunstan  and  others 
may  have  experimented  with  an  iron  of  greater 
purity  than  that  used  by  Cushman. 

Dr.  Cushman  explains  Dunstan's  failure  to  con- 
firm Whitney's  results,  by  arguing  that  by  his 
method  of  operation  he  could  not  have  had  more 
than  o.oooooi  gram  of  iron  in  solution,  and  this 
would  be  too  small  a  quantity  to  detect  by  means  of 
the  phenolphthalein  indicator,  and  yet  would  be 
sufficient  to  induce  corrosion.  He  concludes  that 
the  rusting  of  iron  is  due,  not  to  a  direct  attack  by 
oxygen,  but  by  hydrogen  ions;  in  fact,  as  will  be 
shown  later,  oxygen  may,  under  certain  conditions, 
inhibit  corrosion. 

Dr.  Moody  describes  how  leaving  old  distilled 
water  which  had  been  well  shaken  up  with  air,  in 
contact  with  a  fresh  polished  surface  of  iron,  during 
40  seconds  only,  a  weak  solution  of  potassium  ferri- 
cyanide  detected  iron  in  solution  by  its  blue  colora- 
tion, whereas  when  fresh  distilled  and  unshaken 
water  was  used  no  iron  could  be  detected. 

The  true  cause  of  iron  going  into  solution  re- 
mains perhaps  to  be  found,  but  consideration  of 
the  influence  on  corrosion  of  the  many  impurities 
present  in  iron  and  steel  may,  as  just  stated,  lead 
to  the  correct  solution.  The  subject  will  receive 
further  treatment  in  a  separate  section,  but  the 
author's  theory  of  the  process  of  rusting1,  under  the 


THE  SOLUTION  OF  IRON  IN  WATER         25 

most  favorable  conditions,  may  here  be  restated  as 
follows :  Voltaic  action  between  the  iron  and  its 
impurities,  or,  possibly,  among  the  impurities  them- 
selves, causes  hydrolysis,  or  electrolytic  decomposi- 
tion of  the  water.  If  the  impurities  are  negative  to 
the  iron,  iron  goes  into  solution;  if  the  impurities 
are  positive,  they  themselves  dissolve  and  the  iron 
remains  immune.  The  function  of  the  free  dis- 
sociated hydrogen  derived  from  the  water  (as 
against  combined  hydrogen,  to  be  considered  later) 
is  of  a  catalytic  nature.  The  free  hydrogen  is 
negative  to  the  iron,  and  by  its 'contact  effect  causes 
its  solution.  The  fact  is,  hydrogen  and  iron  cannot 
exist  in  contact  without  creating  a  difference  of 
potential. 

If  the  impurities  are  positive  to  the  iron,  the 
solution  of  the  latter  is  the  second  step  in  rusting ; 
the  decomposition  of  water  to  supply  hydrogen  ions 
is  the  first,  unless  these  ions  are  supplied  by  other 
means,  such  as  acids  or  occlusion.  This  free  hydro- 
gen must  not  be  confounded  with  the  molecular  or 
gaseous  hydrogen  which  is  given  off  during  the 
process  of  corrosion,  which  has  less  function  than 
significance;  it  is  as  much  an  effect  of  the  process 
as  the  rust  itself. 

The  product  of  rapid  electrolysis  of  water  by  an 
electric  current  is  two  atoms  of  hydrogen  and  one 
of  oxygen ;  the  slow  reaction  of  rusting  results, 
apparently,  in  the  formation  of  an  atom  of  hydro- 
gen and  one  of  hydroxyl ;  that  a  difference  of  this 
nature  should  exist  is  not  surprising;  as  we  have 


26    THE  CORROSION  OF  IRON  AND  STEEL 

already  seen,  different  rates  of  oxidation  produce 
different  oxides.  Once  the  iron  is  in  solution,  it  is 
oxidized  by  any  free  oxygen  present. 

With  rise  of  temperature,  the  readiness  of  iron 
to  oxidize  increases.  Hot  iron  decomposes  steam, 
yielding  an  impure  hydrogen  and  is  oxidized ;  cor- 
rosion is  brought  about  by  a  similar  action,  but 
very  much  slower,  voltaic  electricity  taking  the 
place  of  heat.  The  quicker  the  reaction,  the  higher 
the  oxide.  Very  slow  oxidation  gives  rise  to  FeO, 
which  cannot  exist  permanently  as  such  in  the 
presence  of  oxygen.  At  high  temperatures  CO2  is 
reduced  to  CO  in  the  presence  of  iron,  which  is 
then  oxidized  to  Fe3O4. 


ACTION  OF  HYDROGEN  AND  OCCLUDED  GASES 

If  there  are  negative  impurities,  other  than  hy- 
drogen, in  the  iron  or  in  contact  with  it,  iron  will 
go  into  solution,  as  already  stated,  and  rust  will 
appear  and  continue  to  form  until  these  impurities 
are  exhausted  and  provided,  of  course,  the  rust  is 
removed  to  preclude  its  own  contact-effect  on  the 
metal.  With  ordinary  irons,  therefore,  the  primary 
cause  of  corrosion  may  well  be  the  impurities,  but 
their  action  can  hardly  account  for  the  rapid  growth 
of  the  rust.  The  contact-effect  of  hydrogen  has 
been  suggested  as  the  most  potent  factor,  and  the 
de  Meritens  process  of  artificial  corrosion  has  been 
brought  forward  in  confirmation  thereof ;  in  this 
process  the  presence  of  occluded  hydrogen  is  essen- 
tial to  corrosion. 

Graham  found  that  iron  cooled  in  hydrogen  ab- 
sorbed 46  per  cent  of  its  volume.  Prof.  John 
Perry  in  iS/2-1  detected  the  presence  of  hydrogen 
in  steel.  Ledebur  found  0.0017  per  cent  of  hydro- 
gen in  a  soft  open-hearth  steel.  The  electrolytic 
activity  of  hydrogen  was  pointed  out  by  Roberts- 
Austen.22 

According  to  Lenz,  45  per  cent  of  the  absorbed 
gases  in  iron  may  be  hydrogen,  the  balance  being 

27 


28       THE  CORROSION  OF  IRON  AND  STEEL 

carbonic  dioxide,  carbonic  oxide  and  nitrogen  in 
about  equal  proportions.  According  to  F.  C.  G. 
Miilleiva  about  67.8  to  90.3  per  cent  of  the  gas  in 
steel  is  pure  hydrogen. 

In  some  more  recent  investigations  by  O.  Bau- 
douard,2*  the  following  percentage  weights  of  gases 
were  found  in  commercial  iron : 

CO2          H          CO  N  Total 

Wire,   0.5   m.m.   diam 0.035  0.0032  0.047  0.0105  0.0957 

Wire,    i.    m.m.   diam 0.035  0.0017  0.062  0.0042  0.1029 

Sheet,    i.    m.m.    thick 0.012  0.0018  0.081  0.0042  0.0990 

Bar,    10.    m.m.    sq 0.021  0.0056  0.180  0.0141  0.2207 

It  is  a  well-known  fact  that  iron  or  steel  contain- 
ing occluded  hydrogen,  due  to  pickling  in  acids,  is 
hardened  to  a  considerable  extent  and  quickly  oxi- 
dizes while  in  that  condition;  thorough  washing 
and  neutralizing  of  the  acid  will  not  correct  the 
hardness  nor  the  readiness  to  oxidize.  Gas  occlu- 
sion by  this  method  may,  normally,  reach  12  times 
the  volume  of  the  iron,  proving  that  most  of  it 
must  be  alloyed  or  in  a  liquid  or  solid  state.  The 
greater  proportion  of  this  absorbed  gas  is  hydrogen. 

On  the  other  hand,  electrolytically  produced  iron, 
which  is  quite  difficult  to  corrode,  is  hardened  to  a 
considerable  extent  by  the  absorption  of  hydrogen 
during  its  deposition.  The  hardness  of  electrolytic 
iron  is  5.5,  as  against  4.5  for  ordinary  iron.  Ac- 
cording to  Cailletet25  it  will  hold  as  much  as  250 
times  its  own  volume  of  hydrogen,  and  the  alloy 
containing  0.028  per  cent  (by  weight)  of  hydrogen 
will  scratch  glass.  This  absorbed  hydrogen  must 
be  relatively  pure,  and  while  this  may  preclude 
electrochemical  activity  among  the  gases  themselves 


HYDROGEN  AND  OCCLUDED  GASES          29 

it  can  hardly  have  much  bearing  on  the  difference 
of  behavior  between  it  and  pickled  iron,  when 
exposed  to  corroding  agencies. 

The  hydrogen  contained  in  pickled  iron  can  be 
almost  entirely  baked  out  of  it  at  a  low  temperature  ; 
not  so  with  the  hydrogen  absorbed  electrolytically. 
This  tends  to  show  that  in  the  pickled  iron,  the  gas 
is  not  so  permanently  or  stably  combined — if  com- 
bined at  all — as  in  electrolytic  iron.  Furthermore, 
the  great  volume  of  the  gas  taken  in  by  the  electro- 
lytic iron  shows  that  a  very  large  percentage  must 
exist  in  solution  as  an  alloy  with  the  iron.  ,The  co- 
existence of  three  states  of  matter  has  been 
supported  by  Graham,  Wiedermann  and  Spring. 
While  there  may  be  just  as  much  free  dissociated 
hydrogen  contained  in  the  pores  of  both  classes  of 
iron  and  the  tendency  to  rust  from  that  cause  may 
be  the  same,  yet  the  larger  amount  of  hydrogen- 
iron  alloy  in  the  electrolytic  iron  may  resist  corro- 
sion much  better  than  iron  alone. 

The  quality  of  resistivity  to  corrosion  is  inti- 
mately connected  with  the  rise  in  electrical  con- 
ductivity which  is  brought  about  by  the  chemical 
union  of  hydrogen  with  metals.  Hot  iron  when 
quenched  in  water  absorbs  hydrogen,  and  Richards 
and  Behr2G  have  found  that  the  electrode  potential 
was  raised  by  0.15  volt,  the  nature  of  the  gas  being 
apparently  the  same  as  that  which  is  absorbed  in 
the  presence  of  nascent  hydrogen  and  therefore 
by  electrolysis.  The  hydrogen  taken  up  by  finely 
powdered  iron  reduced  at  a  low  temperature  was 


30       THE  CORROSION  OF  IRON  AND  STEEL 

not  found  to  affect  the  e.m.f . ;  we  may  infer  that 
the  physical  conditions  attending  the  production  of 
this  iron  were  insufficiently  powerful  to  cause  the 
alloying  on  which  the  change  of  e.m.f.  seems  to 
depend.  Dr.  Steinmetz  finds  that  electrolytic  iron 
has  a  very  high  hysteresis  loss,  but  attributes  it  to 
occluded  nitrogen. 

From  an  examination  of  all  these  facts,  it  would 
appear  that  the  increase  of  potential  due  to  the 
alloyed  hydrogen  in  electrolytic  iron  overcomes  the 
effect,  as  an  electro-negative  catalyzer  or  otherwise, 
of  hydrogen  in  a  free  ionic  state  only.  In  all 
classes  of  iron  the  hydrogen  exists  in  both  condi- 
tions, free  and  combined,  just  as  carbon  does  in 
pig-iron,  but  the  proportion  of  hydrogen-iron  alloy 
in  electrolytic  iron  is  very  much  greater  than  in 
the  other  metals.  Hydrogen,  like  carbon,  when 
present  in  a  free  state  will  by  contact  action  pro- 
mote corrosion;  like  carbon,  also,  when  chemically 
combined  with  the  iron  it  will  resist  corrosion,  but 
if  the  alloy  is  unevenly  distributed  the  pure  iron  in 
contact  with  the  alloy  will  be  attacked. 

According  to  Roberts-Austen,  silicon,  manga- 
nese and  aluminium  prevent  the  escape  of  hydrogen 
from  iron ;  Ledebur  claims,-7  ho\vever,  that  brittle- 
ness  after  pickling,  due  to  hydrogen,  is  greater  if 
the  combined  carbon  is  high,  while  silicon  has  the 
reverse  effect ;  he  is  in  accord  therefore  with  Troost 
and  Hautefeuille,28  who  claim  that  silicon  diminishes 
absorption.  These  seemingly  opposite  statements 
may  be  reconciled  by  assuming  that,  while  silicon 


HYDROGEN  AND  OCCLUDED  GASES  31 

• 

may  reduce  the  absorption  of  hydrogen,  it  will  also 
retard  its  subsequent  removal  just  as  non-conductors 
which  absorb  heat  with  great  difficulty  will,  on  that 
very  account,  retain  it  the  easier.  Manganese  is 
said1'8  to  greatly  increase  the  absorption  of  the  gas 
while  diminishing  that  of  carbonic  oxide,  which  is, 
in  any  case,  very  slight.  Manganiferous  pig-iron 
retains  more  gas  than  does  ordinary  pig. 

Pressure  applied  during  the  solidification  of 
metals — as,  for  instance,  in  the  Whitworth  process 
—prevents  the  escape  of  the  gases.  They  can  be 
driven  out  by  heating,  preferably  in  vacuo,  or 
locally  by  machining  or  drilling;  the  combination 
is,  therefore,  not  a  very  close  one.  To  drive  the 
gases  out  of  pig-iron,  a  temperature  of  800  deg.  C. 
is  sufficient.  Malleable  iron  contains  more  carbonic 
oxide  than  hydrogen  and  it  is  retained  with  greater 
energy.  Steel  is  said  to  absorb  somewhat  less  than 
cast-iron,  and  wrought-iron  less  than  cast-iron; 
these  differences  are,  in  great  measure,  no  doubt, 
functions  of  the  porosity. 

Occluded  gases,  and  especially  hydrogen,  must 
not  be  lost  sight  of  when  dealing  with  the  problem 
of  corrosion.  Hydrogen  is  the  lightest  and,  there- 
fore, kinetically  the  most  active  of  elements;  it 
seems  to  be  in  a  way  a  sort  of  universal  catalyzing 
"daemon,"  an  extravagant  statement  to  the  ear, 
perhaps,  and  decidedly  questionable,  but  with  some 
merit  of  suggestiveness ;  all  chemical  reactions  take 
place  in  the  presence  of  hydrogen,  if  only  as  a 
trace  of  moisture  or  of  a  volatile  hydrocarbon,  and 


32       THE  CORROSION  OF  IRON  AND  STEEL 

it  is  the  only  element  of  which  this  is  true.  Hydro- 
gen, which  seems  to  form  the  main  ejection  from 
the  sun,  and  may  be  regarded  as  closest  to  the  pri- 
mordial element  from  which,  according  to  recent 
well-grounded  theories,  all  other  elements  may  pro- 
ceed, is  unique  in  many  of  its  properties  ;  it  seems  to 
stand  apart  from  the  other  elements  in  many  ways. 
These  differences  are,  in  many  cases,  attributable 
to  the  great  activity  of  its  molecules  in  proportion 
to  their  mass,  hence,  for  instance,  the  distinct  char- 
acter of  its  curve  representing  the  value  off  pv 
under  different  pressures. 

The  diffusion  through  a  finely  porous  material 
which  gives  rise  to  dissociation  is  similar  to,  if  not 
identical  with,  osmosis ;  in  osmosis  the  porous  mem- 
brane causes  dissociation  resulting  in  chemical  ef- 
fects which  are  the  basis  of  important  reactions 
and,  among  others,  of  organic  growth  and  life. 

Hydrogen  will  pass  through  platinum  and  red- 
hot  iron  (Ste.  Claire-Deville)  and  its  ready  dissocia- 
tion, which  was  demonstrated  in  Winklemann's  im- 
portant study  of  its  diffusion  through  palladium,29 
suggests  a  belief  in  its  breakdown,  under  conditions 
of  common  occurrence,  into  free  and  active  atoms, 
ready  to  take  the  first  opportunity  offered  of  enter- 
ing into  a  combination.  The  condition  of  most 
common  occurrence  is,  as  we  have  seen,  the  con- 
tact of  dissimilar  substances.  The  occlusion  of  free 
hydrogen  in  coal-dust,  wheat-dust,  zinc-dust  and 
other  dusts  will  go  far  to  account  for  their  de- 
tonation by  spontaneous  oxidation.  These  dusts  act 


HYDROGEN  AND  OCCLUDED  GASES 

in  the  same  way  as  does  spongy  platinum  on  cer- 
tain gases  which  it  ignites  by  simple  contact.  Ac- 
tivity in  all  these  cases  is,  in  great  measure,  a 
function  of  the  surface  exposed,  hence  a  porous 
metal  is  more  readily  oxidized  than  one  which  is 
solid.  Whether  or  not  the  surface  of  iron  may  act 
as  a  porous  membrane  and  aid  dissociation  is  a 
matter  for  discussion. 

According  to  a  theory  due  to  Hittorf,  which  may 
now  be  applied  to  the  subject,  when  the  solution 
has  assumed  a  positive  charge  which  counterbalances 
the  negative  charge  on  the  surface  of  the  metal, 
there  is  an  arrest  of  solubility  due  to  the  formation 
of  an  "electrolytic  double-layer,"  a  sort  of  neutral 
film.  If  hydrogen  ions  are  present,  molecular  hy- 
drogen is  precipitated,  because  iron  is  positive  to 
hydrogen,  or,  as  is  often  said,  has  a  greater  "solu- 
tion pressure."  The  precipitated  hydrogen  carries 
positive  electricity  out  of  the  solution ;  then  the 
solution  is  supposed  to  try  to  make  up  for  this  loss 
by  taking  the  positive  element  of  the  double-layer 
which  is  thus  broken  down,  and  solution  of  the  iron 
proceeds. 

The  hydrogen  is,  necessarily,  precipitated  at  nega- 
tive points,  either  on  the  iron  itself — which  implies 
its  being  non-homogeneous — or  on  any  negative 
substance  which  may  be  present,  either  in  the  solu- 
tion or  as  a  so-called  contact  substance.  Copper. 
for  instance,  being  negative  to  iron,  will,  by  aiding 
the  precipitation  of  hydrogen,  favor  the  solution 
of  iron.  Rust  has  already  been  mentioned  as  hav- 


34      THE  CORROSION  OF  IRON  AND  STEEL 

ing  the  same  effect.  Concentration  of  hydrogen 
ions  favor  solution,  hence  the  action  of  acids ;  con- 
centration of  hydroxyl  ions  inhibit  solution,  hence 
the  action  of  alkalis. 

As  already  suggested,  the  dissociation  of  water 
by  the  action  between  iron  and  its  impurities  will 
furnish  the  necessary  hydrogen  ions ;  occlusion  of 
hydrogen  (though  not  alloying  with  it)  will  have  a 
similar  effect.  The  theory  of  solution-tension,  as 
an  intrinsic  property  of  iron,  is  perhaps  superfluous ; 
at  any  rate,  its  nature  has  received  no  rational  ex- 
planation ;  we  have  no  proof  of  its  existence  in  the 
case  of  strictly  pure  metals  immersed  in  strictly 
pure  solvents,  but  we  do  know  that  it  possesses 
a  curve  which  points  to  °  for  these  ideal  condi- 
tions. 

The  solubility  of  metals  through  local  currents 
(Auren  and  Palmaer)  due  to  impurities  or  varia- 
tions in  structure  is  readily  understood. 

It  is  really  the  same  thing  whether  hydrogen 
occluded  in.  a  piece  of  pickled  iron  be  said  to  in- 
crease solubility  by  breaking  down  a  "double-layer" 
or  by  galvanic  action  which  drives  the  iron  into 
solution  in  the  effort  to  restore  electrostatic  equilib- 
rium; whichever  way  it  is  explained,  the  solubility 
is  due  to  hydrogen  giving  iron  a  positive  polarity; 
this  polarity  will  cause  its  solution  whether  there 
be  a  neutral  film  or  not — for,  after  all,  a  neutral 
film  is  equal  to  nothing.  Whether  the  horse  be  put 
in  front  of  the  cart  or  behind  it,  the  cart  moves  and 
the  horse  moves  it;  either  way,  the  horse  is  the 


HYDROGEN  AND  OCCLUDED  GASES  35 

cause  and  not  the  effect  of  the  motion.  So  it  is 
with  hydrogen  in  corrosion ;  it  is  essentially  a  cause, 
although,  as  stated  before,  it  may  neither  be  the 
first  nor  the  whole  cause. 


THE  FUNCTION  OF  OXYGEN 

Under  the  title  of  "The  Function  of  Oxygen  in 
the  Corrosion  of  Metals/';i°  Dr.  W.  H.  Walker  has 
contributed  a  most  valuable  discussion  to  the  chem- 
ical literature  of  corrosion. 

It  is  universally  agreed  that  rusting  requires  free 
oxygen.  Whatever  theory  of  corrosion  is  adopted, 
one  essential  function  of  oxygen  is  to  convert  either 
Fe  or  FeO  into  Fe,O3,  rust. 

Dr.  Walker  lays  stress  on  another  function  of 
oxygen,  giving  it,  in  fact,  first  place;  this  function 
is  the  removal  of  the  layer  of  gaseous  hydrogen 
which  may  accumulate  on  the  surface  of  the  iron 
and  arrest  further  action.  This  is  the  well-known 
effect  presenting  itself  in  electric  batteries  and 
called  "polarization."  Oxidizing  agents,  known  as 
depolarizers,  will  remove  this  film  of  hydrogen, 
allowing  decomposition  to  proceed.  As  we  shall 
see  later,  certain  depolarizers,  such  as  the  bichro- 
mates of  sodium  and  of  potassium,  between  certain 
concentrations,  have  just  the  reverse  effect ;  they 
inhibit  rusting.  The  reasons  for  this  will  be  fully 
discussed,  but  it  may  be  well  to  state  here  that  the 
effect  of  the  chromates  supports  the  theory  that 
hydrogen  is  removed  from  contact  with  the  iron 


THE  FUNCTION  OF  OXYGEN  37 

and  even  replaced  by  the  dissociated  oxygen,  which 
is  electro-positive  to  iron  and  protects  it  after  its 
removal  from  the  solution  of  the  chromate,  by 
bearing,  the  entire  weight  of  the  attack  by  hydro- 
gen. Electro-negative  metals,  such  as  copper  and 
lead,  act  as  depolarizers  and  hasten  the  rusting  of 
iron  or  steel  with  which  they  are  in  contact. 

That  the  removal  of  molecular  hydrogen  is  a 
most  necessary  function  of  oxygen  in  corrosion  is 
an  important  fact  to  remember.  Oxygen  having 
thus  two  functions,  it  is  doubly  important  to  heed 
Dr.  Walker's  plea  for  the  removal  of  air  from 
boiler-feed  waters. 

In  the  article  already  referred  to,  Heyn  and 
Bauer  draw  the  following  conclusions,  among 
others,  regarding  oxygen:  i.  Free  oxygen  is  nec- 
essary for  rusting.  2.  Iron  is  an  extremely  sen- 
sitive qualitative  reagent  for  oxygen  dissolved  in 
water.  3.  In  an  atmosphere  of  pure  oxygen,  rust- 
ing is  three  times  as  rapid  as  in  air.  4.  If  air  is 
bubbled  through  the  water  rusting  takes  place  about 
twice  as  rapidly  as  when  the  air  is  merely  in  con- 
tact with  the  surface  of  the  liquid. 


THE  DIFFERENCE  BETWEEN  IRON  AND  STEEL. 

The  principal  difference  between  iron  and  steel 
lies  in  the  carbon  content.  Iron  having  over  0.04 
per  cent  of  carbon  is  usually  called  steel;  if  there 
is  less  than  about  0.15  per  cent  it  is  known  as  a 
mild  steel.  Save  in  the  arrangement  and  distribu- 
tion of  the  constituents,  it  cannot  be  said  that,  chem- 
ically speaking,  there  is  any  sharp  line  of  demarca- 
tion between  iron  and  steel,  but  the  processes  of 
manufacture  are  different  and  the  two  metals  have 
therefore  different  physical  properties. 

Steels,  with  the  exception  of  the  very  mild  ones, 
are  susceptible  to  being  hardened,  and  it  is  well 
to  note  that  steels  harden  by  changes  in  the  car- 
bides, whereas  chilled  iron  is  hard  because  of  a 
change  in  the  structure  of  the  surface  from  crystal- 
line to  amorphous,  or  nearly  so. 

Carbon  is  present  in  iron  and  steel,  either  as 
microscopic  flat  crystals  of  graphite  or  as  carbides 
of  iron,  of  which  a  number  of  varieties  are  known, 
more  or  less  distinct  from  each  other.  The  most 
common  one  is  cementite,  a  definite  compound, 
Fe.5C ;  pearlite,  an  intimate  mixture  of  cementite 
and  ferrite  (pure  iron)  forms  the  bulk  of  most 

38 


DIFFERENCE  BETWEEN  IRON  AND  STEEL  39 

steels,  and  martensite  is  the  carbide  produced  by 
sudden  cooling.  Sulphur,  phosphorus  and  silicon 
are  present  as  sulphides,  phosphides  and  silicides. 
Manganese,  which  is  added  as  ferro-manganese  in 
the  process  of  manufacture  to  prevent  the  occlusion 
of  gases,  is  always  present  either  alloyed  or  in  com- 
bination with  the  non-metallic  impurities.  In  spe- 
cial steels  there  may  be  nickel,  chromium,  tungsten, 
molybdenum,  vanadium,  etc.  If  the  impurities  are 
not  dissolved  in  the  iron  they  will  separate  as 
eutectics ;  this  will  depend  in  great  measure  on  the 
heat  treatment  and  mode  of  copling. 


THE   STRUCTURE  OF  IRON  AND  STEEL. 

The  normal  structure  of  iron  and  steel  is  crystal- 
line ;  fibrous  iron  is  a  misnomer ;  the  fibrous  appear- 
ance is  due  to  the  way  in  which  the  crystals  draw 
out  from  each  other  in  the  direction  of  their  main 
axes  when  the  metal  is  fractured.  The  more  slowly 
and  uniformly  the  heating  and  cooling  have  been  car- 
ried out,  and  the  less  interference  there  has  been 
by  mechanical  distortion,  the  more  regular  and 
small  will  the  crystals  be;  these  crystals  always  lie 
in  the  direction  of  the  heat  waves  passing  out  in 
cooling;  they  are,  therefore,  at  right  angles  to  the 
contour  planes  of  the  piece ;  it  is  on  this  account 
that  sharp  angles  are  to  be  avoided  in  cast  metal 
work,  as  they  cause  a  sudden  change  of  direction 
in  the  position  of  the  crystals.  When  cast-iron  is 
"chilled"  it  appears  to  be  set  in  a  more  or  less 
amorphous  condition,  hence  its  lack  of  flexibility. 

A  change  in  the  crystalline  structure  of  iron  may 
be  brought  about  by  shock  or  continual  vibration ; 
the  fracture  becomes  coarser  and  there  is  a  simulta- 
neous loss  of  strength  :  the  iron  is  said  to  be  crystal- 
lized. The  strains  which  alter  the  mechanical  con- 
dition of  matter  are:  crushing,  tensile,  flexional  or 
torsional.  The  factors  governing  variations  in  the 

40 


THE  STRUCTURE  OF  IRON  AND  STEEL       41 

results  will  vary  according  to  the  moment  of  the 
strain,  or  its  average  intensity  multiplied  by  the 
period  during  which  it  acts.  The  effects  of  strain 
will  also  vary  in  different  parts  of  the  same  piece 
from  differences  in  the  original  heating,  lamination, 
forging  or  cooling  which  it  may  have  undergone. 
Shearing,  punching  and  other  operations  will  alter 
the  structure;  the  walls  of  a  cold-punched  hole  are 
unfit  for  threading  because  they  are  disaggregated, 
hence  they  should  be  drilled  or  reamed  out.  Swag- 
ing, unless  performed  gradually  and  at  very  high 
speed,  will  have  a  tendency  to  crush  the  material 
and  make  it  "short,"  whereas  light,  rapid  swaging 
and  drawing  through  dies  will  tend  to  interlock  the 
crystals.  If  annealing  is  required  after  drawing 
wire  and  sheets,  it  is  because  the  crystals  are  not 
as  regularly  and  snugly  packed  by  exterior  mechan- 
ical means  as  they  are  by  the  crystallogenic  forces 
which  act  during  cooling  from  high  temperatures. 
It  is  evident,  then,  that  all  manufactured  goods 
must  be  more  or  less  heterogeneous  in  their 
structure. 


RELATION  OF  STRUCTURE  TO  CORROSION 

It  is  found  that,  apart  from  chemical  and  vol- 
taic causes,  corrosion  will  vary  according  to  the 
structure  of  the  material  and  the  mechanical  treat- 
ment to  which  it  has  been  subjected.  It  is  also 
known  that  metals  in  large  masses  will  not  corrode 
as  rapidly  in  proportion  to  the  surface  exposed  as 
will  smaller  masses  of  the  same  composition  and 
in  the  same  physical  condition.  The  reasons  gov- 
erning these  facts  are  still  obscure,  notwithstanding 
the  many  plausible  theories  which  can  be  advanced. 

Hard  cast-iron  is  less  corrodible  than  soft  cast- 
iron  of  similar  composition,31  and  it  corrodes  faster 
if  cooled  irregularly  than  if  cooled  uniformly  and 
slowly.  The  inner  portions,  being  more  uniform 
in  texture,  corrode  more  uniformly  and  slowly 
(Mallet).  The  more  porous  the  material,  the  more 
rapidly  will  corrosion  proceed  and  the  more  deep 
and  destructive  will  it  be.  Blowholes  of  any  size 
invite  rust.  It  has  been  found  that  iron  gun- 
barrels  corrode  more  rapidly  in  wet  weather  than 
those  made  of  compressed  steel  (W.  A.  Adams). 
The  part  of  a  pipe  along  the  weld,  which  has  been 
somewhat  compressed,  in  the  closing  operation, 

42 


RELATION  OF  STRUCTURE  TO  CORROSION  43 

does  not  rust  as  rapidly  as  the  part  opposite  the 
weld.  As  first  discovered  by  Kalischer,  metals 
conduct  electricity  better  when  their  structure  is 
crystalline;  an  amorphous  metallic  foil  which  has 
been  rendered  crystalline  by  careful  heat  treatment 
will  become  a  better  conductor.  Increased  con- 
ductivity implies  better  resistance  to  corrosion. 

The  microscopic  porosity  of  iron  and  steel  has 
been  shown  and  even  measured  by  Thorner.3'- 
Under  ordinary  circumstances,  water  cannot  pass 
through  the  pores  and  fissures  in  iron,  on  account 
of  their  capillary  action,  but  a1  high  pressure  will 
overcome  this  capillarity,  as  shown  in  the  ''sweat- 
ing" of  hydraulic  presses.  The  absorption  of  gases 
likewise  proves  the  porosity  of  iron  and  steel.  At 
high  temperatures  all  metals  absorb  gases,  losing 
part  of  them  again  upon  cooling.  As  already 
stated,  all  manufactured  iron  and  steel  goods  have 
to  undergo  some  form  of  heat  treatment  and  are 
found  to  contain  hydrogen,  nitrogen  and  sometimes 
carbonic  oxide. 

Carelessness  of  manufacture  which  tends  to  het- 
erogeneousness  is  an  invitation  to  corrosion  and  in 
itself  goes  far  to  explain  why  modern  steel,  which 
is  tortured  into  shape  at  such  a  high  speed  that  the 
molecules  are  not  permitted  to  readjust  themselves, 
is  said  to  be  more  corrodible  than  the  metals  pro- 
duced a  generation  ago;  in  those  days  iron  was 
produced  in  small  quantities,  without  the  addition 
of  other  metals,  and  was  rolled  slowly  and  allowed 
to  cool  naturally.  The  internal  strains  due  to  me- 


44       THE  CORROSION  OF  IRON  AND  STEEL 

chanical  treatment  are  not  to  be  confounded  with 
the  unevennesses  in  the  distribution  of.  the  impuri- 
ties due  to  segregation  in  cooling;  these  mechan- 
ically induced  strains  are  really  equivalent  to  strain- 
ing the  metal  beyond  the  elastic  limit,  which,  as 
will  be  seen  later,  makes  it  more  corrodible.  More- 
over, the  tonnage-craze  from  which  the  quality  of 
product  in  so  many  industries  is  to-day  suffering, 
is  causing  to  be  placed  on  the  market  a  great  mass 
of  material,  only  a  small  portion  of  which  is  prop- 
erly inspected,  which  is  not  in  proper  condition  to 
do  its  work — rails  and  axles  which  fail  in  service 
and  steel  skeletons  for  high  buildings  which  may 
carry  in  them  the  germs  of  destruction  and  death. 


EFFECT  OF  STRESS  ox  CORROSION 

"The  effect  of  stress  on  the  corrosion  of  metals" 
is  the  title  of  an  instructive  paper  by  Thomas 
Andrews,  published  in  i894,33  in  which  the  results 
of  extensive  electrolytic  tests,  tensile,  torsional  and 
flexional,  made  in  saline  solutions  are  recorded.  In 
all  classes  of  tests  the  results  were  of  the  same 
nature ;  the  unstrained  parts  were,  by  galvanometer 
readings,  shown  to  be  electro-positive  to  the  strained 
parts  and  h'ence  more  subject  to  corrosion.  On  the 
other  hand,  according  to  experiments  made  in 
France  that  same  year,  if  iron  and  steel  are  strained 
beyond  their  elastic  limit,  the  surface  corrodes  with 
greater  rapidity  along  the  lines  of  deformation, 
where  molecular  cohesion  has  been  broken  down 
and  the  metal  been  made  more  porous.  The  au- 
thor's own  observations  of  overstrained  bolts  con- 
firm this  view,  and  it  is  a  well-established  fact  that 
the  metal  around  punched  holes  will  rust  more 
rapidly  than  that  around  drilled  holes,  because  the 
degrees  of  strain  differ. 

Dr.  Chas.  F.  Burgess  found34  that  in  steel  strained 
tensionally  and  torsionally  to  just  below  the  point 
of  rupture,  the  strained  parts  corroded  very  much 
faster  than  the  unstrained ;  the  unstrained  ends 

45 


46       THE  CORROSION  OF  IRON  AND  STEEL 

being  cathodes,  bubbles  of  hydrogen  were  given  off 
from  them  under  water.  These  results  in  no  way 
invalidate  those  of  Andrews;  Dr.  Burgess  worked 
with  pieces  strained  beyond  the  elastic  limit,  and 
they  had  undergone  permanent  structural  deforma- 
tion, whereas  Andrews  worked  within  the  safe 
limits  allowed  by  engineers,  where  no  permanent 
deformation  within  a  long  period  of  time  is  to  be 
feared. 

In  recent  experiments  made  by  E.  Rasclr5  it 
was  found  that  during  tensile  tests  of  brass  and 
mild  steel,  within  the  elastic  range,  the  metal  became 
cooler,  and  beyond  the  critical  point  or  elastic  limit 
it  became  hotter.  A  loss  of  heat  is  to  be  expected 
during  structural  breakdown,  and  its  connection 
with  the  change  of  electrical  conductivity  is  evi- 
dent. Some  years  ago  A.  Witkowski  found36  that 
in  a  strained  metal  there  is  an  increase  of  electrical 
resistance  in  the  direction  of  the  strain. 

All  these  observations  go  to  prove  the  claim  that 
mechanical  treatment,  by  setting  up  uneven  strains 
in  different  parts  of  finished  pieces,  will  create 
variations  of  potential  which  will  promote  rusting. 
Whatever  the  composition  of  the  different  inner 
parts  of  the  metal  may  be,  and  apart  from  any 
action  which  may  be  due  to  difference  of  composi- 
tion, if  there  is  a  difference  of  molecular  aggrega- 
tion, it  will  promote  the  rusting  of  one  or  other 
of  those  parts.  Action,  power,  everything  know- 
able  depends  on  difference  of  potential,  and  any 
chemical  or  physical  difference  between  two  por- 


EFFECT  OF  STRESS  ON  CORROSION  47 

tions  of  matter  in  contact  must  give  rise  to  a  dif- 
ference of  potential  and  a  flow  of  electricity. 

If  straining  a  metal  below  its  elastic  limit  by 
exteriorly  applied  mechanical  means  will  make  it 
electro-negative  to  the  same  metal  unstrained,  the 
strains  set  up  by  chilling  or  hardening  should  have 
a  like  effect ;  the  metal  should  resist  corrosion  to  a 
greater  extent  and  promote  the  corrosion  of  more 
positive  metals  in  contact  with  it. .  This  is  found 
to  be  the  case.  Eighty  years  ago  Daniell  observed 
that  a  certain  steel  was  dissolved  by  hydrochloric 
acid  five  times  as  rapidly  when  unhardened  as  it 
did  when  hardened ;  this  is  an  indication  of  what 
we  may  expect  with  the  agents  of  corrosion.  Prof. 
Chas.  E.  Munroe37  mentioned  the  case  of  a  cold- 
chisel,  tempered  at  the  end,  which  had  been  dropped 
into  an  engine-room  channel-way  of  the  S.  S. 
Triana  in  1874;  when  found,  some  years  later,  the 
hardened  part  was  not  corroded,  but  the  soft  part 
was,  and  especially  so  at  the  line  of  immersion  in 
tempering,  which  was  clearly  defined;  at  this  point 
the  contact-action  was,  of  course,  most  pronounced ; 
had  the  chisel  been  hardened  throughout,  it  would, 
no  doubt,  have  rusted  all  over;  as  it  is,  however, 
the  soft  part  protected  the  tempered  end,  just  as 
zinc  will  protect  iron  under  similar  circumstances. 

"What  becomes  of  the  energy  of  a  coiled  watch 
spring  when  it  is  dissolved  in  acid?"  is  supposed  to 
be  one  of  the  many  unsolved  mysteries  of  Science. 
The  energy  of  the  coiled  watch  spring  is  indicated 
by  a  slight  shift  of  its  potential  towards  the  nega- 


48       THE  CORROSION  OF  IRON  AND  STEEL 

tive  end  of  the  electro-chemical  scale,  resulting  in 
an  increase  of  e.m.f . ;  when  the  spring  is  put  in 
acid,  the  energy  is  expended  in  retarding  the  action 
of  the  acid  and  is  equivalent  to  a  drop  of  tem- 
perature which  would  restrain  chemical  action. 
The  energy  of  the  spring,  as  increased  e.m.f.,  coun- 
teracts the  energy  of  the  acid ;  it  is  expended  and 
disappears  as  work  of  a  negative  character. 


COMPARATIVE  CORROSION  OF  IRON  AND  STEEL 

From  a  theoretical  standpoint,  steel,  being  nega- 
tive to  iron,  should  be  the  least  corrodible  of  the 
two.  As  a  general  thing,  results  of  tests  between 
iron  and  steel  have,  in  the  past,  resulted  in  favor 
of  the  iron ;  in  most  cases,  the,  experimenters  were 
undoubtedly  looking  for  the  defeat  of  the  new  ma- 
terial, steel,  and  their  state  of  mind  helped  them  to 
find  it.  Some  of  them  were  iron  manufacturers 
who  had  much  to  lose  by  the  adoption  of  steel. 
There  are,  however,  a  large  and  ever  increasing 
number  of  contrary  observations  recorded,  espe- 
cially where  the  tests  have  been  carried  out  with 
qualities  of  recent  manufacture.  The  opinion  one. 
is  led  to  form  from  a  careful  examination  of  re- 
corded observations  is  in  agreement  with  that  of 
Ewing  Matheson,38  namely,  that  properly  protected 
steel  and  iron  rust  to  about  the  same  extent,  the 
steel  doing  so  more  uniformly;  this  is,  of  course, 
subject  to  the  variations  of  structure  already  re- 
ferred to,  and  those  of  chemical  composition,  espe- 
cially as  regards  metallic  impurities,  which  will  be 
considered  later,  and  limited  by  the  fact  that,  un- 
doubtedly, |the  best  quality  of  charcoal  iron  is  prac- 
tically as  resistant  as  the  best  qualities  of  steel  used 
for  similar  purposes.  / 

49 


50       THE  CORROSION  OF  IRON  AND  STEEL 

An  important  paper  was  presented  before  the 
Institution  of  Civil  Engineers  in  1881  by  David 
Phillips,39  "On  the  comparative  endurance  of  iron 
and  mild  steel  when  exposed  to  corrosive  influ- 
ences"; excellent  cables  are  given,  and  the  general 
conclusions  favor  iron. 

It  must  be  borne  in  mind,  as  a  limitation  to  all 
results  adduced,  that,  while  the  initial  rusting  may 
be  greater  with  either  material,  iron  or  steel,  the 
rates  of  progression  may  be  different  and  may 
bring  about  a  complete  reversal  in  the  final  result ; 
the  material  which  rusted  faster  at  first  may  out- 
live the  other.  This  is  especially  apt  to  be  the 
case  with  forged,  rolled  and  drawn  metals,  which 
are  protected  by  a  dense  skin.  Future  tests  should, 
therefore,  either  be  carried  out  to  destruction,  as 
advocated  by  Howe,  or  else  to  the  point  at  which 
failure  of  the  material  in  service  would  result  from 
loss  of  useful  area. 

A  distinction  must  be  made  here  between  the  cast 
and  wrought  metal :  cast  iron  will  not  rust  as  read- 
ily as  wrought  iron  unless  the  skin  is  removed,  in 
which  case  it  will  rust  faster.  Rough  and  machined 
castings  act  quite  differently. 

The  most  radical  difference  between  wrought  iron 
and  steel  is  the  slag,  which  is  always  present  in  the 
iron ;  while  this  slag  may  protect  the  metal  imme- 
diately beneath  it,  its  contact  effect  on  the  exposed 
iron  surrounding  it  must  more  than  counterbalance 
this  slight  advantage, 


CORROSION  OF  IRON  AND  STEEL 


51 


The  effect  of  slag  has  been  the  cause  of  much 
discussion.  Some  elaim  that  wrought  iron  is  com- 
posed of  bundles  of  fibres,  each  of  which  is  encased 
in  slag.  This  theory  implies  that  at  the  temperature 
of  puddling,  slag  is  able  to  distribute  itself  through- 
out the  metal  as  a  film  of  infinitesimal  thickness. 
As  Speller  states,  \y2  parts  of  cinder  are  expected 
to  protect  98  parts  of  iron ;  further  doubt  is  thrown 
on  this  theory  by  the  fact  that  when  wrought  iron 
is  examined  under  the  microscope  "the  cinder  is 
very  irregularly  distributed  in  strings  and  patches." 

The  author  has  tried  the  effect  of  breaking  down 
this  siliceous  barrier  by  means  of  hydrofluoric  acid. 
The  test  pieces  were  short  lengths  of  wrought  iron 
pipe  of  a  well-known  make.  The  acid  solutions 
were  normal  and  used  in  the  quantities  shown  in 
the  table  below ;  in  two  sets  of  tests  one-tenth  the 
volume  of  normal  hydrofluoric  acid  was  added. 
In  each  case  there  were  four  test  pieces,  each  piece 
being  treated  in  a  separate  vessel.  The  weights  in 
grams  and  percentage  losses  were  as  follows : 


Test. 

Weight 
4  Pieces.    j 

Scaling 
2  hrs.    60  c.c. 

Pickling,  20  hrs.     120  c.c. 

I 

II 

III 

IV 

HjSO, 

118.32 

2.12  %  loss 

11.0 

12.9 

14.9 
26.0 

14.5 
36.7 

11.6  %  loss 
47.3  total  %  loss 

HC1 

117.93     ! 

2.37  %  loss 

11.4 
13.5 

13.7 
25.4 

15.6 
37.0 

13.9  %  loss 
48.  8  total  %  loss 

H2S04 
and  HP 

119.08 

12   Q 
2.25%  loss    :      HI 

13.3 
26.3 

16.0 
38.0 

13.2  %  loss 
49.  5  total  %  loss 

HC1 
and  HP 

118.26 

12  *? 
2.35  %lo?s          £* 

13.1 

25.7 

16.3 
37.7 

15.4  %  loss 
50.  8  total  %  loss 

52      THE  CORROSION  OF  IRON  AND  STEEL 

On  the  theory  of  slag-covered  fibres,  a  great  in- 
crease in  the  solubility  of  the  iron  might  have  been 
expected,  but  such  was  not  the  case.  From  the 
appearance  of  the  pieces  after  each  test,  it  is  evi- 
dent that  the  hydrofluoric  acid  dissolved  the  slag 
yielding  a  smoother  surface.  Taking  into  con- 
sideration the  very  obvious  mechanical  protection 
of  the  iron  by  the  undissolved  slag  in  the  case  of  the 
H2SO4  and  HC1  by  themselves,  it  seems  remark- 
able that  the  differences  were  not  greater. 

According  to  another  line  of  argument,  the  sili- 
cates exist  in  streaks  and  form  a  sort  of  ''fence,"  an 
almost  perfect  barrier  against  the  agents  of  corro- 
sion, say  the  Ironites ;  wide  open  to  those  agents, 
say  the  Steelites ;  to  the  argument  of  the  former 
that  "steel  has  no  fence,"  the  latter  might  reply  that 
it  needs  none,  being  a  wall  in  itself. 

While  the  presence  of  slag  may  be  the  most 
radical  difference  between  the  two  metals,  the  most 
important  one  for  the  present  discussion  is  the 
difference  between  the  amount  and  composition  of 
the  carbides  of  iron. 

The  carbides  of  iron  have  a  greater  specific  heat 
than  iron  itself ;  this  implies  a  high  resistance  to 
corrosion ;  the  difference  varies  directly  as  the  car- 
bon content  and  is,  according  to  Meuthen,40  o.oon 
for  each  0.5  per  cent  of  carbon.  According  to  these 
investigations,  the  specific  heat  of  cementite  is 
0.1581,  whereas  that  of  ferrite  is  0.1432;  these 
values  check  up  closely  by  Kopp's  law  of  molecular 
heat,  A  galvanic  current  must  be  created  by  con- 


CORROSION  OF  IRON  AND  STEEL  53 

tact  of  the  carbides  and  the  ferrite.  A  steel  con- 
taining about  i  per  cent  of  carbon  is  practically  a 
compound  of  carbon  and  iron;  it  is  said  to  be 
''saturated" ;  it  is  a  most  intimate  mixture  of  fer- 
rite and  cementite,  known  as  pearlite;  on  this  ac- 
count it  does  not  pit  readily;  if  by  quenching  from 
a  high  heat  it  is  converted  into  austenite  or  mar- 
tensite,  this  tendency  is  further  inhibited.  The 
author  has  found  that  in  the  case  of  two  identically 
similar  disks  of  steel,  cut  one  after  the  other  from 
the  same  bar,  one  of  them  being  hardened,  but  the 
other  left  soft,  and  exposed  together  for  about  two 
years  to  ordinary  agencies,  the  unhardened  disk 
had  69.1  per  cent  of  its  surface  corroded,  whereas 
the  hardened  disk  had  only  corroded  over  56.8  per 
cent  of  its  surface;  the  difference  is  not  great  (20 
per  cent),  but  it  should  be  mentioned  further  that 
the  rust  on  the  hardened  disk  was  of  a  darker 
shade  than  that  on  the  unhardened  disk,  indicating 
a  difference  in  the  nature  of  the  corrosion. 

Prof.  H.  M.  Howe  offers  the  following  sugges- 
tion41 for  a  line  of  investigation  calculated  to  pro- 
duce a  steel  more  resistant  to  corrosion : 

"Perfectly  pure  metals  are,  in  general,  attacked 
by  chemical  reagents  relatively  slowly.  The  pres- 
ence of  any  substance  in  them  which  does  not  dis- 
solve completely  in  the  metal,  but  gives  rise  to  a 
new  component,  like  the  cementite  of  steel,  accel- 
erates solution,  and  corrosion  is  only  a  form  of 
solution  by  difference  of  potential.  The  difference 
of  potential  is  most  effective,  and  hence  the  activity 


54       THE  CORROSION  OF  IRON  AND  STEEL 

of  dissolving  is  greatest  at  the  surface  of  contact 
of  the  two  dissimilar  constituents.  From  this  we 
should  naturally  expect  that,  with  a  given  quantity 
of  any  foreign  constituent,  such  as  cementite  in 
steel,  the  finer  grained  the  structure  is  the  more 
rapid  would  the  solution  be,  because  the  extent  of 
surface  of  contact  between  the  two  will  increase 
with  the  fineness  of  division. 

"From  this  one  may  reasonably  infer  that  those 
kinds  of  heat  treatment  and  mechanical  treatment 
which  tend  to  leave  the  cementite  in  steel  in  the 
largest  possible  masses  and  herewith  the  smallest 
possible  surface,  will  tend  to  retard  corrosion. 

"The  cementite  in  steel  actually  exists  in  the  form 
of  fine  particles  mixed  up  with  the  iron  in  the  form 
of  pearlite.  If  my  idea  is  correct,  then  the  coarser 
the  pearlite  is  and  the  less  it  is  drawn  out  by  me- 
chanical work,  the  less  rapid  should  be  the  corro- 
sion. 

"The  inference  from  this  would  be  that  steel  or 
iron  which  is  to  resist  corrosion  well  ought  to  be 
finished  at  as  high  a  temperature  as  possible,  so 
that  the  particles  of  cementite  in  the  pearlite  may 
as  far  as  possible  coalesce  and  have  the  minimum 
surface  of  contact  with  the  ferrite  which  encloses 
them. 

"Experiment  alone  could  show  whether  this  infer- 
ence is  correct.  Of  course  other  and  unforeseen 
conditions  may  nullify  the  effect  of  the  coarseness, 
which  is  here  pointed  out  as  a  condition  tending  to 
retard  corrosion.  For  instance,  it  might  turn  out 


CORROSION  OF  IRON  AND  STEEL  55 

that  cementite  in  a  fine  state  of  division  might  act 
more  effectively  as  a  mechanical  barrier  to  the 
progress  of  corrosion  than  the  same  cementite  in 
coarser  particles." 

Prof."  Howe's  point  is  well  taken.  It  agrees 
with  the  observation  of  Heyn  and  Bauer*2  that 
when  overheated  and  non-overheated  metal  of  iden- 
tical compositions  are  placed  in  contact  in  water, 
the  non-overheated  metal  is  more  strongly  rusted 
than  when  placed  therein  alone,  and  protects  the 
overheated  metal. 

In  low  carbon  steels  the  distribution  of  the  pearl- 
ite  must  be  in  scattered  masses,  and  its  effect  must 
be  similar  to  that  of  slag  in  iron;  by  its  very 
nature,  however,  and  on  account  of  the  high  heat 
at  which  Hie  metal  is  worked,  the  carbide  can  dis- 
tribute itself  more  evenly  than  slag  and  this  is 
readily  seen  through  the  microscope. 

Iron  contains  very  little  carbon;  it  is  therefore  a 
loose  mixture  of  ferrite  and  carbides ;  there  are 
spots  of  carbide  scattered  about,  because  there  is  not 
enough  carbon  to  permeate  the  mass  throughout 
and  form  an  alloy,  as  in  the  case  of  steel;  each 
particle  of  carbide  is  a  center  for  the  promotion 
of  rust. 

With  its  report  to  the  American  Society  for 
Testing  Materials  in  1908,  the  Committee  on  Corro- 
sion presented  a  table43  showing  the  rate  of  solution 
of  different  classes  of  iron  and  steel  in  a  20% 
solution  of  sulphuric  acid  applied  during  one  hour. 
While  a  test  of  this  nature  is  entirely  worthless  as 


56      THE  CORROSION  OF  IRON  AND  STEEL 

a  test  for  corrodibility,  the  following  general  analy- 
sis of  the  results  may  be  of  some  interest. 

The  wrought  irons  and  Bessemer  steels  dissolved 
the  most  rapidly,  one  sample  of  wrought  iron  out- 
distancing all  others.  Charcoal-iron,  steel  muck- 
bar  and  wrought  iron  puddled  plates  followed  in 
that  order.  Open-hearth  steels  and  the  high  silicon, 
low  carbon  steel  known  as  "ingot-iron,"  were  the 
least  corroded.  Among  the  special  steels,  most  of 
which  resisted  the  acid  far  better  than  ordinary 
steels,  nickel-steel  easily  led,  followed  by  chromium 
and  vanadium  in  that  order. 

Gruner  has  furnished  some  very  definite  data4* 
on  which  to  reject  the  acid  test  for  all  but  special 
cases.  His  test  plates,  28  in  number,  were  fixed  in 
a  wooden  frame  during  immersion.  The  results 
may  be  summarized  as  follows : 

In  Moist  Air: 

Chrome  steels — Worst  corroded. 
Carbon  steels — 

Tungsten  steels — Least  corroded. 
Gray  cast-irons — Less  than  the  steels. 
White  cast-irons — Less  than  the  gray. 
In  Sea-Water  (action  reversed  almost  throughout)  : 
Hardened  steels — Less  than  annealed  steels. 
Soft  steels — Less   than  manganese  and  chrome 

steels. 

Tungsten  steels — Less  than  carbon  steels. 
Gray  cast-irons — More  than  steels. 
White  cast-irons — More  than  gray. 


CORROSION  OF  IRON  AND  STEEL  57 

In  a  0.5  %  solution  of  sulphuric  acid  the  action 
was  very  similar  to  that  in  sea-water,  the  very  mild 
steels  and  the  high-grade  charcoal-irons  being, 
however,  among  the  least  corroded. 

Gruner  concludes  that  the  acid  test  is  worthless 
as  a  criterion  for  corrosion  in  moist  air.  The 
general  conclusions  from  the  above  results  would 
appear  to  be  that  in  air  steels  are  more  readily 
corroded  than  cast  irons,  whereas  the  reverse  is 
true  in  sea-water  and  in  other  good  conducting 
mediums  in  which  homogeneity  is  of  greater  ac- 
count. 

J.  S.  Unger45  gives  some  interesting  information 
about  recent  tests  carried  out  by  the  Carnegie 
Steel  Co. : 

"We  used  three  varieties  of  wrought  iron,  two 
of  basic  open-hearth  steel,  one  of  Bessemer  steel 
and  one  of  nickel  steel.  We  subjected  them  to 
various  agents,  such  as  sea-water,  10  per  cent 
solution  of  boiling  brine,  I  per  cent  solution  of 
sulphuric  acid  and  i  per  cent  of  ferrous  sulphate, 
made  to  imitate  a  mine  water,  and  the  action  of 
ordinary  well  water,  or  water  that  contained  no 
free  sulphuric  acid,  but  contained  carbonates  and 
sulphates  of  lime  and  magnesia. 

"We  found  after  treating  them  in  the  solvents 
for  about  a  year  the  actions  ranked  in  about  this 
order:  Common  pipe  wrought  iron  was  corroded 
the  most,  then  a  medium  quality  wrought  iron, 
followed  by  a  low-carbon  Bessemer  steel ;  then  by 
the  best  grade  of  wrought  iron,  then  by  open- 


58      THE  CORROSION  OF  IRON  AND  STEEL 

hearth  steel,  each  of  the  open-hearth  steels  being 
corroded  to  about  the  same  extent.  The  material 
that  was  least  corroded  was  open-hearth  nickel 
steel.  Our  object  in  testing  the  open-hearth  steels 
was  to  determine  whether  open-hearth  fire-box 
steel  of  high  or  low  manganese  would  show  a  dif- 
ference in  corrosion. 

"The  plates  under  examination  carried  about  0.22 
and  0.60  manganese.  In  the  tests  they  were 
subjected  to  we  found  very  little  difference.  The 
carbon,  phosphorus  and  sulphur  contents  were 
about  the  same  in  both  plates,  the  difference  being 
in  the  manganese.  Further  experiments  along  this 
direction  led  me  to  believe  that  the  more  impure 
the  substance  the  more  rapid  the  corrosion,  or,  in 
other  words,  the  Bessemer  steel  will  corrode  more 
rapidly  than  open-hearth  steel ;  an  acid  open-hearth 
steel  will  corrode  more  rapidly  than  a  basic  open- 
hearth  steel. 

*'We  have  found  that  in  almost  all  cases  the 
wrought  iron  will  corrode  more  rapidly  than  steel. 
We  have  also  found  that  on  comparing  high  and 
low  carbon  steels  made  by  the  same  process,  such 
as  high  and  low  Bessemer  or  high  and  low  basic 
open-hearth  steels,  that  the  higher  the  carbon,  other 
things  being  equal,  the  more  rapid  the  corrosion." 

As  regards  the  last  sentence,  it  seems  evident 
that  in  a  low-carbon  steel  the  higher  the  carbon  the 
more  numerous  the  centers  from  which  corrosion 
may  start,  the  steel  not  being  saturated,  being,  in 
fact,  a  mixture  of  iron  and  iron  carbides  and  non- 


CORROSION  OF  IRON  AND  STEEL  59 

homogeneous.  The  low  carbon  content  and  free- 
dom from  cinder  explain  the  qualities  of  the  dead- 
soft  open-hearth  basic  material  used  in  America  for 
making  horse  nails,  which  is  misnamed  steel. 

Dr.  K.  F.  Stahl  finds  that  steel  and  iron  tanks 
for  storing  sulphuric  acid  last  equally  well ;  the  steel 
corrodes  more  uniformly;  the  iron  is  eaten  out  in 
streaks,  which  is  no  doubt  due  to  the  streaks  of 
cinder  rolled  out  in  the  plates. 


INFLUENCE  OF  MODERN  CONDITIONS. 

The  prejudice  existing  against  steel  may  be  due 
to  the  changes  in  the  conditions  surrounding  the 
use  of  iron  and  steel,  especially  the  composition  of 
the  waste  gases  of  combustion,  which  pollute  the 
atmosphere,  and  the  employment  of  electricity  for 
lighting  and  transportation.  To  quote  Prof.  H.  M. 
Howe  :46  "The  fact  that  steel  has  come  into  wide 
use  simultaneously  with  a  great  increase  in  the 
sulphurous  acid  in  our  city  air  and  of  strong  elec- 
tric currents  in  our  city  ground  may  well  lead  the 
practical  man,  be  he  hasty  or  cautious,  into  in- 
ferring that  the  rapid  corrosion  of  to-day  is  cer- 
tainly due  to  the  new  material  of  to-day,  steel, 
whereas,  in  fact,  it  may  be  wholly  due  to  the  new 
conditions  of  to-day,  sulphurous  acid  and  electrol- 
ysis." 

According  to  a  recent  analysis  of  freshly  fallen 
snow  at  London,  the  atmosphere  of  that  city  is 
polluted  by  the  following  impurities — the  quantities 
given  are  for  one  gallon  of  melted  snow : 

Solids     (mostly    soot) 19-647  grams 

Various    soluble    substances 0.780 

Sulphuric     acid 0.218 

Sodium    chloride    0.086 

Ammonia    o.oio      " 

60 


INFLUENCE  OF  MODERN   CONDITIONS        01 

Sulphuric  acid  is  purely  an  industrial  impurity 
of  the  air;  it  and  chlorine  are  among  the  most 
active  known  promoters  of  corrosion. 

The  prejudice  against  steel  may  also  be  due  to 
the  fact  that,  whereas  the  iron  of  some  years  ago 
was  more  homogeneous  and  freer  from  slag  than 
the  iron  of  the  present  day,  the  steel  which  is  now 
manufactured  is  perhaps  more  homogeneous  than 
that  which  was  made  during  the  early  years  of  the 
industry,  when  only  small  masses  were  handled. 
In  puddling,  working  on  a  small  scale  will  give  a 
better  iron,  freer  from  impurities,  but  in  steel 
making,  working  on  large  masses  of  metal  will, 
within  certain  limits,  assist  the  diffusion  of  the 
components  by  maintaining  the  metal  throughout 
at  a  more  even  and  higher  temperature  for  a  longer 
period  of  time. 


CORROSION  IN  AIR 

Iron  will  not  corrode  in  air  unless  moisture  is 
present,  and  it  will  not  corrode  in  water  unless  air 
is  present.  This  rule  applies  to  salt-water  also: 
R.  Adie  found47  that  corrosion  did  not  take  place 
in  salt-water  if  air  or  oxygen  was  excluded,  and 
that  alcohol  containing  oxygen  but  no  water  would 
not  cause  corrosion. 

Iron  having  a  specific  gravity  of  7.8,  produced  in 
the  laboratory,  as  against  7.3  for  commercial  pig- 
iron,  is  slightly  oxidizable  in  moist  air,  but  iron 
of  a  specific  gravity  of  8.14  produced  in  the  elec- 
tric furnace  is  scarcely  at  all.48 

Of  the  agents  present  in  the  air  which  accelerate 
rusting,  especially  in  or  near  cities  where  much  fuel 
is  consumed,  sulphur  dioxide  and  soot  are  the  most 
destructive  because  together,  in  the  presence  of 
moisture,  they  conspire  to  produce  sulphuric  acid. 
The  action  is  most  marked  in  railway  tunnels  and 
bridges.  Kent  has  studied  the  action  of  sul- 
phur dioxide  ;49  an  analysis  of  sooty  rust  from  a 
railway  bridge  showed  the  presence  of  sulphur 
dioxide,  sulphuric  acid,  carbonic  acid,  chlorine  and 
ammonia.  Valuable  papers  on  the  decay  of  mate- 
rials in  tropical  climates  were  published  in  i864.no 

62 


CORROSION  IN  FRESH  WATER 

The  impurities  in  fresh  water  vary  with  the 
locality.  Rivers  flowing  through  industrial  towns 
will  contain  hydrochloric  and  sulphuric  acids  and 
acids  due  to  the  decomposition  of  organic  matter; 
all  are  highly  corrosive. 

Carbonic  dioxide,  air  and  excess  of  oxygen,  all 
of  which  will  accelerate  corrosion,  are  present  in  all 
waters  to  a.  varying  extent.  Silica  and  alumina  are 
without  direct  chemical  effect.  The  variable  im- 
purities are  as  follows :  carbonates  of  lime,  iron 
and  magnesium ;  sulphates  of  lime,  potassium  and 
magnesium;  nitrates  of  lime  and  potassium;  lastly., 
the  chlorides  of  sodium,  potassium  and  magnesium, 
which  accelerate  corrosion  to  a  considerable  extent. 
Salts  which,  like  sulphates  and  chlorides,  hydrolyze 
in  solution  to  an  acid  reaction,  promote  rusting  to 
a  greater  extent  than  when  they  remain  neutral. 

Water  near  the  surface  is  more  corrosive  than 
lower  down,  because  of  the  larger  percentage  of 
dissolved  carbonic  dioxide  and  air.  Alternations 
of  wetting  and  airing  will  increase  the  rate  of  cor- 
rosion, and  on  this  account  the  most  vulnerable 
part  of  a  ship's  hull  from  the  outside  is  that  part 


64      THE  CORROSION  OF  IRON  AND  STEEL 

known  as  the  wash-space;  continuous  immersion  is 
less  destructive. 

All  and  any  impurities  in  water  will  accelerate 
corrosion;  if  the  rule  of  uneven  composition  pro- 
moting the  corrosion  of  iron  is  true,  it  must  apply 
to  the  medium  also.  A  heterogeneous  medium 
must,  necessarily,  be  the  seat  of  voltaic  currents, 
the  effects  of  which  would  be  to  supply  the  hydro- 
gen ions  required  to  promote  corrosion. 

In  the  case  of  iron-work  at  the  mouth  of  a  river, 
where  the  water  is  brackish,  strata  of  different  de- 
grees of  salinity  are  to  be  found ;  on  this  account 
the  rate  of  corrosion  is  particularly  rapid  at  the 
point  where  the  water  is  most  salty ;  it  is,  on  a 
large  scale,  the  effect  suggested  as  taking  place  in 
each  drop  of  every  non-homogeneous  medium. 

Rain  water  is  relatively  pure,  but  even  it  will 
contain  salts  dissolved  from  the  dust  in  the  air, 
which  increase  its  conductivity  and  rusting  prop- 
erties. Theoretically  pure  water  would  be  a  non- 
conductor and  could  not,  therefore,  serve  as  the 
electrolyte  in  the  process  of  rusting. 


CORROSION  IN  SALT  WATER. 

In  sea-water  the  proportion  of  chlorides  is  very 
much  greater  than  in  fresh  water;  moreover,  some 
ammonia  and  the  bromides  of  magnesium  and 
iodine,  all  of  them  powerful  aids  to  corrosion,  have 
to  be  reckoned  with.  Sewage,  which  is  almost 
always  present  near  the  mouth  of  rivers,  supplies 
sulphates,  nitrates  and  organic  matter.  According 
to  records,  the  most  salty  seas  are  the  Mediter- 
ranean and  'Dead  seas,  and  the  least  salty  are  the 
Baltic  and  the  Black  seas. 

Saline  matter  in  water  decomposes  in  contact 
with  iron  which  fixes  the  negative  elements ;  it  also 
serves  to  increase  the  conductivity  of  the  water  con- 
sidered as  an  electrolyte  and,  as  already  suggested, 
increases  the  heterogeneousness  of  the  medium,  re- 
sulting in  galvanic  action  in  the  medium  itself  which 
may  supply  hydrogen  ions.  The  most  extensive 
and  complete  investigation  of  the  action  of  sea- 
water  on  the  metals  of  ships  is  due  to  Robert 
Mallet,51  and  he  has  published  some  very  important 
tables. 

When  cast-iron  is  left  in  sea-water  for  a  long 
period  of  time  it  undergoes  a  remarkable  change, 
being  converted  into  a  pseudomorphous  mass  of  a 

65 


66      THE  CORROSION  OF  IRON  AND  STEEL 

black  substance  resembling  plumbago.  As  far  back 
as  1822  it  was  known  that  slightly  acidulated  water 
would  have  this  effect  on  iron,  and  40  years  later 
Dr.  Calvert  found  this  to  be  the  case  with  salt- 
water also.  Guns  from  the  wrecks  of  the  Royal 
George  and  the  Royal  Edgar,  which  had  been  under 
water  62  and  133  years,  respectively,  were  found 
to  have  become  black  and  soft,  so  that  they  could 
be  cut  with  a  knife,  and  when  brought  up  into  the 
air  they  absorbed  oxygen  so  rapidly  that  they 
heated  up.  They  must  have  been  extremely  porous. 
Cast-iron  pipe  used  for  conveying  salt-water  has 
been  known  to  undergo  the  same  transformation.52 
A  piece  of  an  iron  ship's  heel-post,  which  had 
suffered  considerable  decomposition  of  this  nature, 
was  found  by  David  Mushet53  to  be  of  the  follow- 
ing composition : 

Carbon    dioxide    and    moisture 20.0    per    cent. 

Protoxide    of     iron     (FeO) 35.7 

Silt    or   earthy   matter 7.2 

Carbon 41.1 

The  FeO  and  CO2  were  no  doubt  present  mostly 
as  Fe3O4  and  FeCO3. 

Mallet  attributes  the  conversion  of  the  iron  into 
a  plumbago-like  mass  to  the  action  of  the  carbonic 
dioxide  present  in  the  water. 

Some  tests  were  made  in  1882  by  J.  Farquhar- 
son54  on  six  plates  of  iron  and  six  of  steel ;  these 
were  immersed  for  six  months  in  Portsmouth  Har- 
bour, six  of  each  separately,  the  other  six  as  con- 
nected couples ;  in  this  way  the  comparative  corro- 
sion of  the  iron  and  steel  was  obtained  and  also 


CORROSION   IX   SALT   WATER  G7 

the  increase  of  corrosion  due  to  galvanic  action 
between  steel  and  iron.  The  following  table  gives 
the  losses  observed  in  ounces  and  grains : 


(a) 

Steel  1 

in  contact  

0-427 

Iron   j 

7-417 

(b) 

Steel  j. 
Iron   \ 

separate  

3-340 
3-327 

(0 

Steel  ( 

in  contact  

0-297 

Iron  $ 

7-770 

(d) 

Steel  ' 
Iron   f 

separate  

4-000 
"  3-190 

(e) 

Steel  I 
Iron   f 

in  contact  .(  

2-337 
6-OCO 

(f) 

Steel  I 
Iron   f 

separate  

4-157 
4-570 

These  results,  which  were  confirmed  by  Mr.  \Y. 
Denny  from  his  experience  in  the  case  of  the  S.  S. 
Ravenna,  are  interesting  to  analyze.  They  show 
that  in  two  cases  only  did  the  steel  corrode  to  a 
greater  extent  than  the  iron,  but  the  difference  is 
so  slight  that  for  all  practical  purposes  it  can  be 
said  that  the  steel  and  iron  of  the  experiments 
(ship-plates)  were  equally  affected.  They  also 
confirm  the  theory  that  the  combination  of  steel 
and  iron,  which  is  quite  frequent  in  practice,  is 
detrimental  to  the  iron,  but  protects  the  steel,  which 
is  the  negative  partner.  They  also  throw  light  on 
previous  observations  and  lead  to  the  conclusion 
that  good  homogeneous  iron  and  steel  are  about 
equally  corrodible.  As  we  shall  see  later,  the  most 
valuable  advantage  which  steel  possesses  over  iron 
is  due  to  the  fact  of  its  not  pitting  so  deeply. 


68      THE  CORROSION  OF  IRON  AND  STEEL 

Iron  in  contact  with  non-metals  will  also  suffer 
from  galvanic  action,  as  shown  in  the  case  of  a 
bolt  which  was  corroded  almost  entirely  through 
at  the  junction  of  pieces  of  elm  and  pitch-pine, 
which  it  held  together,55  and  the  case  mentioned 
by  Matheson  of  a  piece  of  iron  on  a  bridge  which 
was  corroded  to  a  knife  edge  where  it  came  in 
contact  with  wood. 

The  effects  of  electrolytic  action  are  clearly  dem- 
onstrated by  the  results  secured  by  Mallet  in  a 
series  of  experiments  which  he  undertook  in  order 
to  ascertain  the  "amount  of  corrosion  in  equal  times 
in  clear  sea-water  of  a  unit  surface  of  wrought 
iron  plate  exposed  in  electro-chemical  contact  with 
an  equal  surface  of  the  following  metals  electro- 
negative to  it,  as  compared  with  the  corrosion  of 
the  same  surface  of  the  same  iron  exposed  alone 
for  the  same  length  of  time" : 

Relative 
Corrosion. 

Iron    plate    alone 8.63  per    cent. 

In  contact  with:      Brass    (Cu»  +  Zn) 29.64          " 

Copper      42.79 

Lead     47-90 

dun-metal      (Bronze) 56.39          " 

Tin      74.71 

In  connection  with  the  above  table,  the  valuable 
fact  is  mentioned  that  the  brass  alloys  of  composi- 
tion Cu*  -j-  Zn17  to  Cus  -j-  Znls  are  without  gal- 
vanic action  on  iron  in  sea-water.  The  alloy  of 
iron,  copper,  zinc  (and  sometimes  tin),  which  is 
known  as  Delta  Metal,  tested  under  similar  con- 


CORROSION  IN  SALT  WATER  69 

ditions    with   wrought   iron   and   steel,    showed   re- 
markable resistance,  as  follows  :56 

Wrought  Iron     Steel  Delta  Metal 

Loss    • 45-9  45-45          1-2    per    cent. 

The  first  copper-zinc  alloy  for  the  special  pur- 
pose of  resisting  the  action  of  sea-water  was  pat- 
ented  in  1832  by  G.  F.  Muntz.  Muntz  Metal  is 
used  for  bolts,  valves,  etc.,  and  for  sheathing  ships ; 
its  composition  is  2  parts  zinc  to  3  parts  copper. 
Tobin  bronze  is  similar  to  Delta  Metal,  but  con- 
tains tin  and  lead. 

According  to  Heyn  and  Bauer/"7  cast  iron  pro- 
tects wrought  iron  in  contact  with  it,  and  contact 
with  nickel  will  increase  the  rate  of  corrosion  of 
iron  from  14  to  19%.  The  same  investigators  found 
that  iron  in  contact  with  copper  rusted  25%  faster 
in  ordinary  water  and  47%  faster  in  sea-water. 

The  interior  of  ships  is  subject  to  various  agents 
of  corrosion.  At  certain  points  the  temperature  is 
higher  than  at  others,  and  escaping  steam  keeps 
the  atmosphere  moist;  the  bilge-water  also  is  of  a 
highly  corrosive  character;  the  coal  abrades  the 
sides  of  the  vessel,  holds  moisture  in  contact  with 
them,  and  induces  the  formation  of  sulphuric  acid 
if  sulphur  dioxide  is  present,  besides,  coal  is,  in  the 
presence  of  sea-wrater,  strongly  electro-negative  to 
iron.  Some  cargoes  and  the  fermented  or  decaying 
remnants  of  old  cargoes  are  likewise  aids  to  corro- 
sion. Cement  is  used  for  coating  ship-plates  on 
the  inside,  but  this  prevents  examination  of  the 
hull,  and  it  is  porous  to  moisture  and  gases. 


CORROSION  OF  RAILS 

The  case  of  steel  rails  is  an  interesting  one,  show- 
ing as  it  does  the  effect  of  vibration  on  rusting. 
A  rail  which  has  been  in  service  but  has  been  laid 
to  one  side  will  rust  all  over,  but  especially  at  the 
ends  where  the  vibration  of  the  fish-plates  has  re- 
moved the  mill-scale,  and  on  the  smooth  top  of  the 
head.  On  the  other  hand,  a  quite  remarkable  fact, 
which  has  been  universally  confirmed  and  can  be 
easily  observed  by  any  one,  is  that  a  rail  while  in 
service  will  not  rust  nearly  as  rapidly  as  one  which 
is  lying  out  of  service.  The  rusting  takes  place  in 
proportion  to  the  service,  and  lines  over  which  fast 
trains  pass  frequently,  causing  much  vibration,  will 
practically  not  rust  at  all,  whereas  the  rails  of 
turnouts  or  sidings,  which  undergo  less  service,  and 
that  of  a  slow  nature,  will  rust  to  a  certain  extent. 
One  observer  (J.  M.  Heppel)  has  reported  the  case 
of  some  rails  at  Madras,  India,  which  lost  3  pounds 
to  the  yard  lying  in  the  yard  exposed  to  the  sea 
air,  while  the  rails  in  service  nearby  were  not  per- 
ceptibly affected. 

The  top  of  a  rail  is  compressed  and  smoothed 
down  in  service  by  the  grinding  of  wheel  tires,  for 
there  is  always  a  certain  amount  of  slip,  especially 

70 


CORROSION  OF  RAILS  71 

during  acceleration  and  retardation.  Galvanic  ac- 
tion between  the  smooth  head  of  the  rail  and  the 
rest  of  it  has  been  suggested  to  explain  this  im- 
munity from  rust,  but  it  is  not  at  all  likely  that  the 
foot  would  owe  its  protection  to  the  thin  stratum 
of  denser  metal  so  far  removed  from  it.  If  that 
dense  skin  on  the  top  of  the  rail  were  not  crushed 
beyond  its  elastic  limit,  it  would,  on  the  contrary, 
tend  to  accelerate  the  corrosion  of  the  steel  in 
contact  with  it. 

The  real  reason  for  this  difference  of  behavior 
seems  to  lie  in  the  observed  fact  that  oxidation  is 
apparently  arrested,  or  at  least  greatly  retarded,  by 
vibration.58  Explanations  seem  to  stop  at  this 
point,  but  a  simple  theory  can  be  built  on  the 
assumption  that  the  vibration  causes  a  shedding  of 
the  rust  as  soon  as  it  is  formed  on  the  spots  that 
are  not  protected  by  mill-scale,  and  there  is,  there- 
fore, no  acceleration  of  the  action  due  to  the  accu- 
mulation of  spongy  and  electro-negative  rust.  The 
average  speed  of  corrosion  of  a  vibrating  body 
would  be  that  of  the  formation  of  a  first  film  of 
rust.  Most  of  the  actual  rust  on  rails  is  probably 
due  to  the  rapid  evaporation  of  rain  on  the  surface. 
In  the  case  of  rails  in  service,  the  first  film  of  rust 
would  be  confined  to  bare  spots  and  cracks  in  the 
mill-scale,  and  the  vibration  would  prevent  its  work- 
ing its  way  under  the  mill-scale,  as  would  happen 
if  the  rail  were  at  rest. 

The  top  of  the  rail  being  denser  might  be  ex- 
pected to  resist  corrosion  better  when  the  rail  is 


72       THE  CORROSION  OF  IRON  AND  STEEL 

out  of  use;  such  is  not  the  case,  however.  The 
surface  has  not  only  been  subjected  to  hammering 
and  crushing,  but  also  to  abrasion  and  rolling,  and 
it  has  become  short  and  crackled  and  sometimes 
exfoliated;  once  laid  aside,  the  smooth  top  of  an 
old  rail  rusts  very  rapidly. 


CORROSION  OF  TUBES 

The  carefully  acquired  experience  of  the  largest 
manufacturers  of  tubes  in  the  world,  which  induced 
them  recently  to  abandon  the  manufacture  of 
wrought  iron  pipes,  teaches  that  the  use  of  steel  in 
place  of  iron — at  least  in  the  United  States — for 
the  special  purpose  of  tubing,  is  to  be  preferred; 
the  tendency  of  the  steel  to  pit  is  somewhat  less 
than  that  of  iron,  and  it  welds  at  the  joint  fully  as 
well. 

The  joint  investigations  of  H.  M.  Howe  and 
Bradley  Stoughton  confirm  these  results.  It  must 
be  borne  in  mind  that  the  conclusions  apply  to  skelp 
material  only.  They  are  further  corroborated  by 
experiments  recently  made  by  T.  N.  Thomson,59 
who  finds  that  iron  and  mild  steel  pipes  corrode 
about  equally,  the  steel  having,  however,  the  advan- 
tage in  the  all-important  matter  of  pitting.  In  a 
test  of  three  pieces  of  wrought  iron  and  three  pieces 
of  mild  steel  pipe  conveying  hot  water  during  about 
one  year  under  conditions  identically  the  same,  the 
iron  pipe  lost  by  rusting  20^4  ounces  in  9  13/32 
pounds  (13.4  per  cent),  and  the  steel  pipe  24% 
ounces  in  911/32  pounds  (15.6  per  cent).  The 
experimenter  did  not  stop  short  at  these  figures 

73 


74      THE  CORROSION  OF  IRON  AND  STEEL 

and  argue  therefrom,  as  all  his  predecessors  had 
done,  that  the  steel  pipe  was  inferior  to  the  iron 
pipe  as  a  merchant  article,  although  evidently 
slightly  more  corrodible ;  he  estimated  the  degree 
of  pitting  hy  averaging  the  measured  depth  of  the 
five  deepest  pits  in  each  piece  and  thence  he  calcu- 
lated the  number  of  days  the  pipe  would  remain 
sound  and  not  show  a  leak;  there  is  no  evidence  of 
his  having  taken  into  consideration  the  fact  that  the 
internal  pressure  would  cause  a  leak  before  the 
metal  was  pitted  through;  however,  the  proportions, 
as  shown  in  the  following  table,  would  hold  good : 

Steel  850.4  days  Iron    780.5    days 

780.5  759.7 

759-7  686.5 

Average 796.9  742.2 

The  steel  pipe  was  therefore  54.7  days,  or  7^2 
per  cent,  more  durable  than  the  iron  pipe.  Hot- 
galvanized  pipe  was  found  to  last  about  20  per  cent 
longer  than  the  ungalvanized ;  this  result,  applying 
to  a  few  pieces  of  similar  origin  and  tested  under 
conditions  where  galvanized  pipe  is  unsuitable,  is 
of  little  value.  If  it  were  correct,  galvanizing  would 
not  justify  its  cost. 

Mr.  Thomson  also  draws  the  following  conclu- 
sions from  a  large  number  of  observations  col- 
lected from  all  parts  of  the  United  States :  That 
in  the  case  of  pipe  buried  in  the  ground  and  con- 
veying steam  or  hot  water,  the  exterior  corrodes 
rapidly,  but  when  the  pipe  is  not  buried,  and  unless 
air  and  other  gases  be  removed  from  the  water,  the 
interior  is  corroded  more  rapidly  than  the  exterior. 


CORROSION  OF  TUBES  75 

The  tests  of  Howe  and  Stoughton  and  the  evi- 
dence which  they  have  collected  is  of  great  in- 
terest. Of  ten  different  tests  made  by  different 
observers  in  different  places,  seven  resulted  deci- 
sively in  favor  of  steel ;  in  the  other  three  cases  the 
results  were  very  slightly  in  favor  of  the  iron,  but 
in  only  one  of  the  latter  was  the  material  of  modern 
manufacture.  The  tests  which  resulted  in  favor 
of  steel  were  as  follows,  all  except  the  two  first 
being  carried  to  destruction :  Seven  months  in  hot, 
aerated  salt-water;  sixteen  months  buried  in  damp- 
ened ashes ;  exposed  to  sulphuric  acid  coal-mine 
water;  in  railroad  interlocking  and  signal  service; 
in  locomotive  boiler  service.  It  was  also  found  that 
steel  tubes  made  in  1906  pitted  much  less  than  those 
of  1897  from  the  same  makers,  indicating  the  su- 
periority of  modern  steel  over  that  of  some  years 
back  in  this  particular  respect. 

In  30  complete  service  tests  made  by  railroads 
during  the  years  1907  and  1908,  modern  steel 
tubing  showed  a  slight  superiority  over  so-called 
charcoal-iron  tubing  and  the  rusting  was  more 
uniform.60 

Badly  made  steel  will  evidently  corrode  faster 
than  a  uniform  product,  and  the  question  of  the 
comparative  corrosion  of  iron  and  steel  should  not 
be  judged  from  the  behavior  of  a  poor  quality;  un- 
fortunately, persons  afflicted  with  mental  hustling 
always  generalize  exceptions. 

F.  N.  Speller  has  invented  a  process  of  mechan- 
ical working  or  kneading  of  the  surface  of  the  metal 


76      THE  CORROSION  OF  IRON  AND  STEEl! 

for  tubes  during  rolling  which  has  been  found  to 
improve  its  texture  and  render  it  more  uniform;  the 
process  is  known  as  "spellerizing"  and  is  now  in 
extensive  use.  In  the  following  table  of  corrosion 
tests'11  Nos.  4,  5  and  6  were  on  spellerized  steel. 
Results  are  shown  as  percentages  of  corrosion,  as 
compared  with  iron : 

Test 
No.      Conditions  Authority  Duration      Iron        Steel      Started 

1  Aerated  dist. 
water,  normal 

temperature  U.  S.  Navy          61  weeks  94.5        1901 

2  Sea  water,  nor- 
mal temperature  H.  M.  Howe          2  years         100        119.0        1897 

3  Aerated  brine, 
normal  temper- 
ature Nat.  Tube  Co.       6  mos.          100        106.0        1904 

4  Aerated  water, 

180°  F.  Nat.  Tube  Co.       3  mos.          100          90.6        1906 

5  Aerated  brine, 

180°  F.  Nat.  Tube  Co.       3  mos.          100          75.3        1906 

6  Aerated    sea 

water,  180°  F.      Nat.  Tube  Co.       3  mos.          100          94.2        1906 

The  value  of  the  proofs  adduced  in  defense  of 
steel  pipe  has  been  seriously  questioned,  and,  with 
perfect  justice,  it  has  been  pointed  out0-  that  the 
value  of  short  as  against  long  time  service  tests  is 
a  most  important  one.  In  the  case  of  steel  and  iron 
pipes  put  in  service  20  years  or  more  ago,  the  iron 
pipe  has,  in  all  known  instances,  resisted  corrosion 
far  better  than  the  steel;,  in  recent  short  service 
tests  and  laboratory  tests  the  steel  has  almost  in- 
variably won.  The  difference  may  reside  in  the 
fact  that  modern  steel  does  not  pit  as  readily  as  the 


CORROSION  OF  TUBES  77 

steel  of  some  years  ago,  because  it  is  more  homo- 
geneous, as  indicated  by  its  improved  tensile 
qualities. 

The  'Riverside  Iron  Works  found  that  iron  boiler 
sheets  corroded  faster  than  steel  sheets  when 
buried  in  soil  which  was  kept  moist  with  a  solution 
of  carbonate  of  soda,  nitrate  of  soda,  chloride  of 
ammonium  and  chloride  of  magnesium,  which  are 
among  the  most  active  corroding  substances  com- 
monly found  in  water ;  the  results  were  as  follows  : 

After  23   days  Iron  loss 0.84  per  cent. 

Steel     "     ' 0.72 

28   days  later   Iron   loss 2.06 

Steel     "     1.79 

Boiler  tubes  in  service  will  suffer  severely  if 
exposed  to  the  action  of  fatty  oils  which,  even  if 
perfectly  neutral,  have  a  strongly  corrosive  action 
on  iron  in  the  presence  of  steam.63  Cottonseed  oil, 
which  is  used  as  an  adulterant  of  cylinder  oils, 
must  be  avoided.  The  great  enemies  of  boiler 
tubes  are,  however,  the  sulphuric  acid  and  salts  in 
the  feed-water  and  dissolved  oxygen.  The  former 
can  generally  be  taken  care  of  by  the  use  of  certain 
compounds  or  by  other  chemical  means,  but  the 
latter  is  more  difficult  to  remove  and  demands  spe- 
cial study.  Zinc  is  only  of  value  in  boilers  if  the 
water  is  in  the  condition  of  an  electrolyte,  hence, 
while  good  for  marine  boilers,  it  is  of  little  or  no 
use  in  fresh-water  boilers. 


CORROSION  OF  WIRE  AND  SHEETS. 

In  the  case  of  wire,  the  consensus  of  experience 
seems  to  be  just  the  reverse  from  what  it  is  with 
pipe.  In  his  report  on  "The  Corrosion  of  Fence 
Wire/'01  Dr.  Cushman  quotes  the  opinion  of  a  con- 
cern which  is  a  very  large  consumer  of  wire,  that 
"Bessemer  or  mild  steel  wire  will  rust  or  deteriorate 
much  more  rapidly  than  iron  wire.  In  all  proba- 
bility, three  times  as  rapidly."  He  also  found  that, 
according  to  the  unanimous  opinion  of  farmers, 
modern  steel  wire  fencing  is  much  more  corrodible 
than  the  old  iron  wire.  It  is  difficult  to  see  why 
there  should  be  this  reversal  of  properties  for  wire 
as  compared  with  tubing,  in  view  of  the  fact  that 
steel  wire  has  a  harder  skin  than  iron  wire,  because, 
being  less  malleable  and  being  harder  to  draw 
through  the  dies,  the  packing  of  the  material  at 
the  surface  is  more  marked.  This  is  easily  proved 
by  treating  pieces  of  steel  and  iron  wire  with  an 
acid;  the  acid  eats  out  the  metal  on  the  ends  accord- 
ing to  its  degree  of  porosity,  and  it  is  found  that 
the  steel  wire  shows  a  denser  and  better  defined 
skin  than  the  iron.  In  the  case  of  iron,  the  honey- 

78 


CORROSION  OF  WIRE  AND  SHEETS  79 

combing  extends  much  closer  to  the  edge.  The 
skin  seems  to  resist  the  action  of  the  acid  in  the 
ratio  of  its  density.  The  same  effect  of  acids  may 
be  observed  with  all  rolled  material,  notably  sheets. 
In  its  investigations,  the  Division  of  Tests  of  the 
Department  of  Agriculture  found,  as  would  nat- 
urally be  the  case,  that  modern  steel  wire  was,  on 
an  average,  much  higher  in  manganese  than  the 
old  iron  wire. 

One  might  almost  think  that  in  the  case  of  thin 
material  the  results  are  the  very  opposite  of  what 
they  are  with  heavy  material.  This  may  be  due  to 
the  repeated  pickling  and  drawing  or  rolling,  caus- 
ing cinder  to  accumulate  at  the  surface  in  sufficient 
proportion  relatively  to  the  iron  to  form  a  pro- 
tective layer.  The  condition  of  the  surface  of  iron 
wire  and  sheet  after  it  has  been  etched  would 
tend  to  confirm  this  view. 

As  regards  sheets,  the  published  records  would 
indicate  the  superiority  of  iron  over  steel,  but,  as 
in  the  case  of  tubes,  the  relation  may  be  shifting. 
A  recent  reliable  service  test  of  unprotected  roofing 
sheets65  showed  the  superiority  of  a  low-phosphorus, 
low-sulphur  Bessemer  steel  over  wrought  iron. 

When  a  protective  coating  of  paint,  tar,  tin  or 
zinc  is  applied,  iron  invariably  shows  better  qualities 
than  steel,  but  this  is  due  to  the  fact  that,  on  account 
of  its  rougher  surface  after  cleaning,  iron  will  take 
a  heavier  and  more  closely  adherent  coating  than 
steel. 


80      THE  CORROSION  OF  IRON  AND  STEEL 

A  sheet  made  of  very  pure  iron  is  superior  to 
one  of  mild  steel,  as  shown  by  the  following  tests  :Gfl 

Corrosion  ratios. 
Iron  Sheet     Steel  Sheet 

Cold    sulphuric    acid     (3-6%) 100  1600 

Air    and    moisture 100  280 

Sulphur   dioxide   and  moisture    (cold) 100  112 

Sulphur  dioxide-strong  solution  in  water...  100  108 

The  chemical  composition  of  these  sheets  was  as 
follows : 

Iron   Sheets  Steel  Sheets 

Carbon      0.018 %  0.09   % 

Manganese 0.024%  0.39   % 

Phosphorous      0.040%  0.104% 

Sulphur     0.023%  0.053% 

Silicon     0.036%  


INFLUENCE  OF  THE  IMPURITIES  IN  THE  METAL 

All  non-homogeneous  metals  and  therefore  all 
commercial  irons  and  steels  are  doomed  to  decay 
unless  adequately  protected.  Of  the  impurities  in 
steel,  the  non-metals,  with  the  exception  of  sulphur, 
seem  to  protect.  In  the  case  of  metallic  impurities, 
those  which,  like  manganese,  are  themselves  more 
liable  to  corrosion  than  the  iron,  will  act  unfavor- 
ably ;  others,  like  nickel  and  chromium,  which  are 
not  so  sensitive,  will  protect  the  iron  with  which 
they  are  alloyed,  notwithstanding  the  fact  that  by 
mechanical  contact  they  hasten  the  rusting;  if  un- 
alloyed they  act  adversely,  creating  centers  for 
pitting.  Eutectic  areas  create  centers  for  corrosion. 

The  nature  and  amount  of  the  impurities  in  steel 
have  a  marked  influence  on  its  corrodibility.  Car- 
bon, inasmuch  as  it  will  allow  hardening,  will  act 
as  a  protection,  provided  it  is  combined  with  the 
iron  and  uniformly  distributed ;  high  carbon  steel 
is  less  corrodible  than  mild  steel  or  iron.  Black 
oxide  only  protects  provided  it  is  continuous  and 
firmly  "anchored"  to  the  iron  (Bower-Barfnng. 
etc.)  ;  as  mill-scale  which  is  loose  and  fissured,  it 
is  detrimental,  the  iron  in  contact  with  it  and  ex- 
posed, rusts  about  50%  faster. 

The  gray  cast-iron,  in  which  combined  carbon  is 

81 


82      THE  CORROSION  OF  IRON  AND  STEEL 

deficient,  rusts  more  rapidly  than  other  grades. 
Spiegeleisen07  resists  corrosion  better  than  cast-iron 
because  it  is  dense  and  high  in  carbon.  Prof. 
Howe  calls  attention  to  the  mechanical  protection 
afforded  by  carbon  as  rusting  proceeds,  in  the  fol- 
lowing words  :68  "As  steel  is  gradually  corroded 
away,  more  and  more  of  its  surface  should  come 
to  be  composed  of  cementite,  and  this  fact  should 
tend  to  retard  the  corrosion  of  steel,  because 
cementite  should  protect  the  underlying  free  iron 
or  ferrite."  And  elsewhere :  "The  cementite  is  in 
such  extremely  minute  microscopic  plates  that  the 
eating  away  of  a  very  small  quantity  of  the  iron 
from  above  them  ought  to  bring  very  nearly  the  full 
proportion  of  this  cementite  to  the  surface."  It 
may  be  stated  further  that  the  definite  compound, 
cementite,  is  much  harder  than  iron — 6.5  as  against 
4.5 — and  that  it  is  soluble  only  in  boiling  hot  acids. 

Dr.  W.  L.  Dudley  found00  that  the  presence  of 
coal-gas  in  the  ground  materially  retarded  the  cor- 
rosion of  wrought  iron  pipe  buried  in  it.  In  one 
test  at  Nashville,  the  presence  of  the  gas  reduced 
the  rate  of  corrosion  by  one-half.  It  has  also  been 
found  that  gas-holders  resist  corrosion  well  on  the 
inside,  notwithstanding  the  water  of  condensation. 
Various  methods  of  carbonating  the  surface  of  iron 
and  steel  are  in  use  for  protecting  them  against 
corrosion  and  are  effective  wherever  there  is  little 
or  no  wear. 

Graphite  in  iron,  which  is  equivalent  to  uneven 
distribution  of  carbon,  may  promote  rusting,  but 


INFLUENCE   OF   IMPURITIES  83 

graphite  applied  to  the  outside  is  conceded  to  be 
second  to  red-lead  only  as  a  protection  for  iron 
work  (Archbutt)  ;  this  protection  is,  no  doubt, 
purely  mechanical,  although  Dr.  E.  G.  Acheson 
claims  that  steel,  if  immersed  in  water  containing 
defloculated  graphite,  does  not  rust  as  when  the 
graphite  is  not  added. 

Sulphur  accelerates  corrosion.  According  to 
Moody,70  sulphur  compounds  in  iron  and  steel  on 
exposure  to  air  and  water  at  once  furnish  free  acid. 

Phosphorus  and  silicon  both  appear  to  retard 
corrosion,  and  this  effect  may,  as  in  the  case  of 
carbon,  have  some  connection  with  their  hardening 
qualities,  or  cold-shortening  power.  If,  however, 
they  are  present  in  patches,  like  the  oft-occurring 
phosphide  eutectics,  the  softer  parts,  through  con- 
tact action  with  the  parts  rich  in  phosphorus  and 
silicon,  will  be  destroyed  all  the  more  rapidly. 
Some  authors  have  claimed  that  these  two  elements 
increase  corrosion,  but  there  is  no  evidence  to  sup- 
port the  contention  apart  from  the  case  of  uneven 
distribution,  which  will  make  any  of  the  impurities 
rust  promoters  to  a  greater  or  lesser  extent.  The 
fact  that  common  iron  does  not  rust  as  rapidly  as 
the  better  grades  has  been  attributed  by  some  to 
the  greater  percentage  of  phosphorus  in  the  former. 
It  might  also  be  stated  that  charcoal-iron  is  free 
from  manganese,  and  this  might  bear  some  relation 
to  its  qualities. 

The  alloys  of  silicon  and  iron  which  are  known 
as  "Metillures"  show  remarkable  resistance  both  to 


84      THE  CORROSION  OF  IRON  AND  STEEL 

acid  and  atmospheric  corrosion;  this  resistance  in- 
creases with  the  percentage  of  silicon;  above  a 
content  of  20%  Si  there  is  practically  no  action. 
Unfortunately,  these  alloys  lack  malleability,  but 
apparatus  made  from  them  is  used  under  such 
severe  conditions  as  carrying  and  condensing  hy- 
drochloric acid.71 

Dr.  Dudley  discovered,  some  years  ago,  that  se- 
gregated manganese  formed  centers  of  corrosion, 
and  it  is  a  generally  accepted  fact  that  steels  high 
in  manganese  are  peculiarly  liable  to  oxidation;  if 
the  proportion  is  small  and  uniformly  distributed 
the  effect  is  inconsiderable.  The  effect  of  manga- 
nese is  corroborated  by  many  reliable  authorities. 7- 
The  mixing  of  finely  divided  iron  and  manganese 
and  subsequent  exposure  to  oxidizing  agents  will 
result  in  rapid  oxidation  of  both  metals,  the  man- 
ganese itself  being  oxidized  more  rapidly  than  the 
iron;  if  placed  in  water  the  electrolytic  action  is 
evidenced  by  an  appreciable  and  continuous  dis- 
engag'ement  of  hydrogen.  If  pieces  of  iron  and  man- 
ganese are  connected  the  latter  will  corrode  and 
protect  the  iron  (Walker) .  According  to  R.  Dubois,T:; 
some  ferro-manganese  originally  carrying  79.99  per 
cent  of  manganese  was  partially  disintegrated  by 
exposure  to  the  weather.  The  powdery  part  held 
82.17  per  cent  of  manganese,  and  the  mass  had 
shrunk  to  one-half  of  its  original  bulk;  this  goes  to 
prove  the  instability  of  the  combination  between 
the  two  metals.  It  has  already  been  mentioned  that 
manganese  increases  the  occlusion  of  gases. 


INFLUENCE    OF   IMPURITIES  85 

If  the  metals  are  alloyed  the  alloy  is  more 
electro-positive  than  the  iron  by  itself  and  there- 
fore more  readily  corroded.  Up  to  a  certain  per- 
centage manganese  dissolved  in  iron  will  increase 
the  electrical  resistance  of  the  metal,  and  the  loss 
of  conductivity  may  reach  50  per  cent  (Cushman). 
This  fact  is,  no  doubt,  intimately  connected  with 
its  corrodibility,  the  broad  rule  being  that  the  better 
conductor  a  metal  is  the  less  it  is  liable  to  corro- 
sion ;  the  conductivity  of  a  metal  is  always  reduced 
by  the  addition  of  a  less  conducting  metal;  hydro- 
gen is  in  the  same  class  as  the1  metals.  It  is  known 
that  manganese  salts  fix  oxygen  on  certain  com- 
pounds, and  that  even  the  solid  salts  at  suitable  tem- 
peratures hasten  the  oxidation  of  many  substances ; 
the  metal  itself  will  precipitate  iron  from  its  solu- 
tions, and  it  is  reasonable  to  infer  that  with  iron 
going  into  solution  in  the  presence  of  oxygen,  if 
there  is  any  manganese  present,  it  will  aid  its 
precipitation  as  an  oxide.  As  silicon  has  the  prop- 
erty of  hardening  manganese,  a  small  percentage 
doing  so  to  a  considerable  extent,  the  influence  of 
manganese  in  promoting  corrosion  may  be  modified 
by  that  element. 

The  combination  of  manganese  and  sulphur 
shows  a  larger  difference  of  potential  to  iron  than 
manganese  alone.  The  sulphur  in  steel  will  unite 
more  readily  with  the  manganese  than  with  the 
iron,  giving  a  gray  sulphide.  Some  valuable  in- 
vestigations of  the  effect  of  manganese  sulphide  on 
the  quality  of  rails  have  quite  recently  been  carried 


86      THE  CORROSION  OF  IRON  AND  STEEL 

out  by  Dr.  Henry  Fay  and  J.  E.  Howard.74  These 
investigators  show  that  manganese  sulphide  sepa- 
rated in  the  form  of  fibers  is  a  source  of  danger  in 
steel  rails,  so  that,  apart  from  reasons  relating  to 
corrodibility,  the  combination  of  high  manganese 
and  high  sulphur  is  to  be  avoided  as  a  measure  of 
safety. 

The  protection  afforded  by  paints  containing 
manganese  dioxide  (MnO2),  even  after  their  re- 
moval, seem  to  be  due,  not  to  the  power  which  the 
salt  possesses  of  decomposing  hydrogen  peroxide, 
but  to  the  creation  of  a 'passive  condition  due  to 
the  formation  of  a  film  of  black  oxide  (Wood)  ; 
by  using  a  very  active  oxidizing  agent  in  a  paint,  it 
is  claimed  that  slight  inoxidation  may  be  brought 
about  and  rusting  inhibited;  some  tests  of  this 
theory  made-  within  recent  years  have  not  borne  it 
out.  If  a  Venetian-red  (Fe2O3)  paint  is  used  there 
cannot  be  any  protection,  even  in  theory — and  al- 
most anything  can  be  done  in  theory — all  metals 
are  electro-positive  to  their  own  oxides,  and  on  this 
account  paints  containing  oxides  of  the  metals  to 
be  painted  are  undesirable  from  a  galvanic  stand- 
point. An  ideal  method  for  protecting  steel  against 
corrosion  would  consist  in  giving  it  a  perfectly 
homogeneous  surface  before  painting,  either  by  re- 
moving slag,  manganese,  sulphur  and  other  im- 
purities chemically,  or  by  depositing  electrolytic 
iron  upon  it,  using  a  depolarizer  to  take  care  of  the 
free  hydrogen. 


COMPARATIVE  CORROSION  OF  ACID  AND  BASIC 
STEELS. 

Alexander  G.  Fraser.  in  a  paper  read  before  the 
West  of  Scotland  Iron  and  Steel  Institute  in  lo/)/,75 
gave  the  results  of  an  extensive  investigation  of  the 
relative  corrodibility  of  acid  and  basic  steels. 

Excepting  in  the  sulphuric  acid  test,  the  acid  steel 
was  a  trifle  less  attacked  than  the  basic ;  this  may 
have  been  due  to  the  manganese  being  higher  in 
the  basic  steel,  although  the  phosphorus  was  lower. 
In  the  case  of  the  sulphuric  acid  test  (sp.  gr.  1.05) 
the  basic  steel  resisted  far  better  than  did  the  acid 
steel  to  the  extent  of  from  8.43  to  26.24%  ;  the 
skin  of  the  basic  steel  plates  was  scarcely  attacked, 
whereas  most  of  the  acid  plates  were  badly  cor- 
roded. Mr.  Fraser  suggested  that  this  might  have 
been  due  to  the  carbon  being  in  a  different  condi- 
tion in  the  two  steels  and  a  sort  of  case-hardening 
of  the  surface  of  the  basic  plates  having  taken 
place  during  rolling;  this  would  vitiate  judgment  as 
applied  to  the  body  of  the  metals.  From  the  fig- 
ures given  in  the  table  it  would  appear  that  the 
popular  notion  about  the  excessive  corrodibility  of 
basic  steel  is  unfounded. 


S7 


INFLUENCE  OF  THE  ELECTRIC  CURRENT. 

Interesting  tests  of  the  effect  of  an  electric  cur- 
rent on  the  speed  of  corrosion  of  a  steel  plate  were 
made  by  Mr.  Gardner,  of  the  Scientific  Section  of 
the  American  Paint  Manufacturers'  Association;78 
the  results  of  the  normal  tests  without  current 
under  different  conditions  are  worth  comparing 
with  those  of  earlier  experimenters,  but  the  in- 
crease in  the  rate,  due  to  the  passage  of  a  current 
of  il/2  volt,  is  specially  worthy  of  attention.  The 
following  is  a  summary  of  the  results : 

1 .  Distilled     water     boiled 0.0482 

i A.  Same  with  electric   current 0.0870 

2.  Distilled   water  and   oxygen 0.0601 

2 A.  Same   with    electric   current 0.1211 

3.  Distilled    water    and    ozone 0.0768 

3 A.  Same    with    electric    current 0.1155 

4.  Pure   air,   oxygen   and    nitrogen 0.0492 

4 A.  Same   with   electric  current 0.091 1 

5.  Pure  air,  with  ammonia;   oxygen,   nitrogen   and  ammonia.  0.0406 

(Little  oxide  precipitated.     Color  dark.) 

5 A.  Same    with    electric    current 0.0758 

(Little  oxide  precipitated.     Color  dark.) 

6.  Pure   air   with    ammonia;    oxygen,    nitrogen   and   carbonic 

acid     0.1030 

(Color  of  oxide  brighter  than   any  of  foregoing.) 

6 A.  Same    with    electric    current 0.1941 

(Color  of  oxide  brighter  than   any  of  foregoing.) 

7.  Pure  air  with  ammonia  and  carbonic   acid 0.0921 

(Color  of  oxide  brighter  than   any  of  foregoing.) 

7 A.  Same    with    electric    current 0.1876 

(Color  of  oxide  brighter  than  any  of  foregoing.) 

In  each  case  the  action  seems  to  have  been  about 
doubled  in  its  intensity  by  the  passage  of  the  cur- 
rent. 

Alternating  currents  have  less  effect  on  the  cor- 
rosion of  iron  than  direct  currents  (Gee). 

88 


IRON  AND  STEEL  EMBEDDED  IN  CONCRETE 

Reinforced  concrete  is  undoubtedly  the  building 
material  of  the  future,  because  of  the  wide  distribu- 
tion of  cement  material  and  also  because  this  com- 
bination of  concrete  and  steel  has  proved  itself 
within  the  last  few  years  the  best  for  every  purpose 
and  from  all  points  of  view  e.xcept,  possibly,  that 
of  beauty  of  form.  The  one  and  only  serious 
objection  which  has  been  raised  against  it  is  the 
permanence  of  the  reinforcement;  it  is  a  question 
of  paramount  interest. 

In  reinforced  concrete  construction  the  steel  re- 
inforcement gives  the  material  the  requisite  quality 
for  undergoing  flexional  strains  under  which  con- 
crete by  itself  would  fail,  as  would  natural  stone, 
notwithstanding  its  high  resistance  to  crushing.  To 
take  advantage  of  its  qualities,  the  reinforcement 
must  be  placed  below  the  concrete,  although  addi- 
tional reinforcement  may  be  required  on  the  upper 
part  to  take  care  of  negative  bending  moments. 
The  mortar  which  is  applied  to  the  other  side  of 
the  reinforcement — the  lower  side  in  the  case  of 
floors  and  beams — must  be  sufficient  to  protect  it 
against  fire  and  corrosion.  The  lighter  coating  is 
usually  il/2  inch  or  more  in  thickness,  depending  on 
its  composition,  and  therefore  its  ability  to  resist 


90      THE  CORROSION  OF  IRON  AND  STEEL 

the  disintegrating  effect  of  fire  applied  for  a  long 
time ;  its  composition  should  be  such  as  to  afford 
full  protection  against  corrosion.  It  is  remarkable 
but  true  that  but  little  attention  is  paid  to  the  latter 
consideration,  although  it  is  fully  as  important  as 
the  protection  against  fire. 

The  majority  of  tests  which  have  been  undertaken 
to  secure  data  on  the  corrodibility  of  steel  in  con- 
crete have  resulted  in  the  broad  conclusion  that 
when  properly  mixed  and  applied,  Portland  cement 
concrete  is  an  ideal  protection  against  rusting. 
There  is  a  well-known  case  of  iron  hoops  embedded 
in  cement  for  26  years,  which  were  found  unim- 
paired and  with  the  blue  mill-scale  intact.77 
Whether  or  not,  as  claimed  by  Breuille,  cement 
removes  any  rust  which  may  have  existed  on  the 
metal  when  it  was  embedded  is  of  secondary  im- 
portance compared  to  the  action  it  may  have  on  the 
unimpaired  metal. 

Neat  Portland  cement  is  known  to  be  an  excel- 
lent protection  against  rusting;  it  has  been  suc- 
cessfully used  as  paint  for  the  protection  of  large 
structures,  notwithstanding  its  lack  of  flexibility. 
On  account  of  this  quality  it  is  well  to  endeavor, 
wherever  possible,  to  fill  in  and  around  the  rein- 
forcement and  in  immediate  contact  with  its  surface 
with  a  concrete  high  in  cement  and  holding  a 
smaller  percentage  of  small  gravel  or  broken  stone 
than  what  is  to  be  laid  above  it;  it  should  also  be 
applied  very  wet  to  insure  good  contact  and  the 
formation  of  a  film  of  neat  cement  on  the  surface 


IRON  AND  STEEL  IN  CONCRETE     91 

of  the  reinforcement;  for  the  protective  coating  a 
rich  mortar,  as  wet  as  can  be  used,  is  advisable. 

Prof.  S.  B.  Xewberry  has  explained  as  follows 
the  protective  action  of  Portland  cement:  "Port- 
land cement  contains  about  63  per  cent  lime.  By 
the  action  of  water  it  is  converted  into  a  crystalline 
mass  of  hydrated  calcium  silicate  and  calcium  hy- 
drate. In  hardening  it  rapidly  absorbs  carbonic 
acid  and  becomes  coated  on  the  surface  with  a  film 
of  carbonate,  cement  mortar  thus  acting  as  an  effi- 
cient protector  of  iron,  and  captures  and  imprisons 
every  carbonic-acid  molecule  that  threatens  to  attack 
the  metal.  The  action  is,  therefore,  not  due  to  the 
exclusion  of  the  air,  and  even  though  the  concrete 
be  porous,,  and  not  in  contact  with  the  metal  at  all 
points,  it  will  still  filter  and  neutralize  the  acid  and 
prevent  its  corrosive  effect."  This  explanation  will 
no  doubt  satisfy  the  followers  of  the  carbonic-acid 
theory  of  corrosion,  but  the  fact  will  remain  that 
at  points  where  there  is  no  contact  between  the 
cement  and  the  metal  corrosion  does  quite  often 
take  place ;  however,  the  protection  against  car- 
bonic acid  afforded  by  the  cement  must  be  an  effi- 
cient retarder  of  corrosion.  An  insoluble  carbonate 
is  an  excellent  impermeable  screen  against  corrosive 
influences,  and  its  value  is  well  illustrated  by  the 
remarkable  passivity  of  sheet-zinc  roofing  which 
has  been  weathering  for  scores  of  years  on  thou- 
sands of  buildings  in  European  cities. 

With  many  styles  of  reinforcement,  it  is  difficult 
to  employ  a  selected  strength  of  mix  in  immediate 


92      THE  CORROSION  OF  IRON  AND  STEEL 

contact  with  the  steel;  with  reinforcements  made 
from  sheet  metal  it  can,  as  a  rule,  be  readily  done. 
Plain  rods  would  seem  to  be  the  best  to  use,  de- 
formed ones  being  liable  to  cause  air-pockets. 
Prof.  Chas.  L.  Norton  has  made  tests  which  show 
that  while  neat  cement  affords  perfect  protection 
to  steel,  concrete  does  not;  it  is  thus  of  the  very 
greatest  importance  that  the  cement  be  sufficiently 
wet  to  insure  a  film  of  neat  cement  forming  on  the 
surface  of  the  reinforcement,  and  that  the  concrete 
be  everywhere  well  rammed. 

As  far  as  subsequent  rusting  is  concerned,  it 
would  seem  to  be  of  little  importance  whether  the 
reinforcement  be  clean  and  free  from  rust  or  not 
at  the  time  of  embedding,  provided  the  concrete  lie 
close  to  it  and  form  an  impermeable  skin  over  it; 
it  is,  however,  an  important  consideration  to  secure 
proper  adhesion  of  the  steel  to  the  cement.  Espe- 
cially is  this  necessary  in  the  case  of  wire,  which 
must  not  draw  through  the  cement  in  case  an 
anchorage  fails  or  it  is  rusted  through  at  one  point. 
Galvanizing  or  painting  the  reinforcement  is  a  pure 
waste  of  money,  and  both  are  liable  to  introduce 
agents  of  corrosion,  such  as  chlorides,  metallic 
oxides  and  organic  acids ;  they  furthermore  prevent 
the  proper  adhesion  of  the  cement.  A  dip  of  tar 
asphaltum  would  perhaps  be  beneficial;  the  best 
practice  is,  perhaps,  to  dip  the  reinforcement  in  a 
neat  cement  grout  before  using  it.78 

Cinder  concrete  is  more  porous  than  that  which 
contains  a  stone  filler,  and  opposes  less  resistance 


IRON  AND  STEEL  IN  CONCRETE  93 

to  shear,  and  for  these  reasons  it  is  less  desirable 
in  reinforced  work;  it  is  still  a  matter  of  some 
doubt  if  the  small  amounts  of  sulphur  and  iron 
oxide  which  are  present  in  the  cinder  can  have  any 
effect  worth  considering  on  the  reinforcement;  it 
is,  however,  not  advisable  to  use  it  around  the  rein- 
forcement, especially  where,  as  in  the  case  of  wire, 
"splitting"  is  to  be  avoided.  For  similar  reasons 
it  is  best  not  to  use  slag  cement  until  it  has  been 
definitely  proved  that  steel  is  no  more  liable  to 
rust  in  it  than  in  genuine  Portland  concrete. 

According  to  Breuille,  if  wafer  is  allowed  to  pass 
through  the  concrete  the  neat  cement  film  in  con- 
tact with  the  steel  will  disappear  and  rusting  will 
take  place;  it  is  thus  advisable  to  waterproof  ex- 
posed surfaces — as  is  always  done  in  the  case  of 
roofing — or  to  use  an  opaque  reinforcement  such 
as  specially  crimped  or  corrugated  sheets ;  even 
then  the  water,  if  it  cannot  go  through,  will  work 
its  way  out  laterally.  If  acids  or  other  corrosive 
liquids  can  reach  the  reinforcement,  special  surface 
protection  of  the  concrete  is-  imperative. 

Cement  has  been  used  for  the  inside  of  ships  to 
protect  the  hull  against  the  internal  corroding 
agencies  which  are  the  most  severe.  Barges,  pon- 
toons, floating  stages  and  even  row-boats  have  been 
built  entirely  of  reinforced  concrete.  This  system 
was  first  used  for  boats  and  pontoons  by  Lambot- 
Miraval,  a  Frenchman,  in  1850. 

There  is  a  great  deal  of  literature  published  on 
the  subject  of  reinforced  concrete,  and  the  conclu- 


94      THE  CORROSION  OF  IRON  AND  STEEL 

sions  to  be  derived  from  it  are  that  it  is  safe  to 
use  modern  rustable  steel  reinforcement,  provided 
it  is  clean,  and  a  coating  of  neat  Portland  cement 
on  its  surface  is  insured  by  using  a  rich  and  wet 
mix  with  clean  sand  and  trap  rock,  limestone  or 
other  hard  and  passive  filler,  in  immediate  contact 
with  it,  and  avoiding  voids  by  careful  tamping. 
The  fact  that  concrete  structures  are  monolithic 
and  become  stronger  with  age  and  also  because  the 
factors  of  safety  allowed  are — and  should  remain 
— conservative,  we  are  justified  in  feeling  convinced 
of  their  permanence,  even  if  through  carelessness 
during  erection  the  reinforcements  suffer  a  partial 
decay.  It  would  be  unwise,  however,  not  to  provide 
against  such  decay  and  to  allow  it  to  go  to  the 
length  of  total  destruction. 


THE  INHIBITION  OF  RUSTING 

By  the  inhibition  of  rusting  is  meant  its  restric- 
tion or  repression,  not  its  complete  prohibition; 
inhibition  means  an  extension  of  life  for  the  iron; 
the  protective  effect  is,  sooner  or  later,  overcome 
and  clearly  indicates  that  inhibition  furnishes  some- 
thing to  the  iron,  be  it  substance  or  physical  state, 
which,  under  the  attacks  of  corrosive  agencies,  is 
slowly  expended  until  destroyed  or  brought  below 
the  safe  limit  of  protection. 

Inhibitory  treatments  have  the  effect  of  render- 
ing the  iron  or  steel  passive.  Passivity  to  chemical 
action  may  have  a  mechanical  or  electrical  cause. 
In  some  cases  it  seems  to  be  due  to  the  formation 
of  a  neutral  screen  between  the  corroding  agents 
and  the  iron ;  in  other  cases  it  seems  to  be  due  to  a 
zone  of  occluded  matter  or  gas  which  affords  gal- 
vanic protection.  This  last  is  apparently  the  nature 
of  the  protection  afforded  iron  which  has  undergone 
any  of  the  inhibitory  treatments  which  have  so  far 
been  tried. 

The  fact,  pointed  out  by  Dr.  Cushman,  that 
treated  iron  will  take  on  an  adherent  coating  of 
copper  from  a  sulphate  solution  in  less  than  one- 
sixth  the  time  required  when  it  is  untreated,  is 


96      THE  CORROSION  OF  IRON  AND  STEEL 

sufficient  proof  that  the  electrolytic  action  which 
causes  the  precipitation  of  the  copper  has  been  in- 
tensified by  the  inhibitory  treatment;  the  difference 
of  e.m.f.  between  the  copper  ions  and  the  iron  is 
greater.  The  investigator  points  out  further  that 
the  protective  effect  can  evidently  not  be  due  to  a 
film  of  oxide.79 

That  strong  oxidizing  agents  would  render  iron 
passive  has  been  known  for  a  long  time.  Prof. 
Bloxam  in  i86880  showed  that  iron  which  had  been 
dipped  in  pure  nitric  acid  for  a  length  of  time  was 
not  affected  by  the  same  acid  dilute.  The  fuming 
sulphuric  acid  will  have  a  similar  effect.  Arsenic 
and  its  derivatives  likewise  inhibit  rusting.81  Moody 
mentions  also  sodium  nitrite  and  potassium  ferro- 
cyanide. 

The  best  way  to  examine  the  subject  of  inhibition 
is  to  take  advantage  of  the  work  of  Dr.  Cushman 
and  analyze  the  following  facts,  expressed  in  his 
own  words : 

1.  "All  substances  which  develop  hydroxyl  ions 
in  solution,  such  as  the  alkalis  or  salts  of  strong 
bases  with  weak  acids,  to  a  certain  extent  inhibit, 
and,  if  the  concentration  is  high  enough,  absolutely 
prohibit  the  rusting  of  iron." 

2.  "No  rusting  occurred  in  any  solutions  of  or 
above  a  strength  corresponding  to  about  8  parts  of 
potassium  bichromate  in  100,000  parts  of  water,  or 
about  2  pounds  to  3,000  gallons." 

In  both  of  these  cases  the  objects  treated  were 
kept  in  the  treating  solutions.  Potassium  bichro- 


THE  INHIBITION  OF  RUSTING  97 

mate  and  chromic  acid  appear  to  be  of  benefit  for 
retarding  the  inception  of  rusting,  under  proper 
conditions  of  concentration  and  condition  of  the 
surfaces  treated. 

3.  "No  visible  change  is  effected,  for  the  pol- 
ished surfaces  examined  under  the  microscope  ap- 
pear to  be  untouched.     If,   however,  the  polished 
strips  are  immersed  in  water,  it  will  be  found  that 
rusting  is  inhibited  for  a  matter  of  hours,  days  or 
even  weeks." 

The  impossibility  of  detecting  any  change  tends 
to  show  that  no  chemical  alteration  of  the  surface 
has  taken  place;  the  final  overcoming  of  the  pro- 
tection by  corroding  agencies  shows  that  the  attacks 
of  those  agencies  exhaust  the  power  accumulated 
by  the  treatment,  and  that,  therefore,  some  kind 
of  destructive  effect  on  whatever  was  left  in  the 
iron  by  the  treatment  is  taking  place,  until  finally 
the  metal  loses  its  immunity  and  is  corroded  in  the 
ordinary  way. 

Moody  explains  the  action  of  chromic  acid  as  due 
to  the  removal  of  constituents  which  would  yield 
acids  on  exposure  to  water  and  oxygen.  He  claims 
that  iron  is  dissolved  in  chromic  acid  and  that 
chromated  iron  is  oxidized  in  normal  air  contain- 
ing CO2.  Actual  experiments  with  properly  chro- 
mated steel  does  not  confirm  its  corrodibility  in 
normal  air. 

4.  "If  a  polished  surface,  which  has  been  ren- 
dered   passive    by    immersion    in    bichromate,    is 
heated  to  100°  C.  for  some  hours,  its  passivity  dis- 


98      THE  CORROSION  OF  IRON  AND  STEEL 

appears  and  it  again  behaves  in  a  normal  mannner." 

5.  "A  chromated  strip  of  iron  which  is  kept  in  a 
vacuum  soon  loses  its  passivity,  whereas  a  similar 
strip  kept  under  ordinary  conditions  remains  pas- 
sive for  long  periods." 

These  last  two  facts  are  strongly  suggestive  of  the 
presence  of  an  occluded  gas,  which  can  be  baked 
out  or  diffused  out  in  a  vacuum. 

6.  "The  phenomenon  of  passivity  is   produced 
only    by    strong   oxidizing    agents    or    by   galvanic 
contact  when  oxygen  can  separate  on  the  iron." 

As  we  have  seen,  when  iron  is  anode  and  dis- 
solves it  will  rust,  and  hydrogen,  which  is  negative 
to  it,  will  be  precipitated.  In  the  present  case  we 
have  the  condition  of  oxygen  being  precipitated, 
showing  that  the  iron  is  cathode.  In  the  case  of 
rusting  we  had  free  dissociated  hydrogen,  inducing 
corrosion  by  its  contact  effect  on  the  iron,  now  we 
have  free  dissociated  oxygen  inhibiting  rusting  by 
what  we  may  well  be  allowed  to  surmise  is  likewise 
a  contact  effect.  Hydrogen,  which  in  itself  is  sug- 
gestive of  reduction,  is  the  indicator  of  the  oppo- 
site reaction  of  oxidation,  and  oxygen,  which  sug- 
gests oxidation,  is  the  indicator  of  reduction.  This 
fact  is  very  well  illustrated  in  the  process  of  pickling 
by  electricity,82  in  which  the  metal  to  be  pickled  is 
put  in  a  weak  acid  solution  and  connected  as 
cathode  in  a  circuit  of  low  voltage,  whereby  the 
scale  is  rapidly  reduced. 

7.  "According  to  Mugclan,83  the  passivity  is  due 
to  lowering  of  the  potential  of  the  metal." 


THE  INHIBITION  OF  RUSTING  99 

8.  "If  polished  iron  is  allowed  to  stand  for  some 
time  in  standard  tenth-normal  potassium  bichro- 
mate solution,  the  oxidizing  strength  of  the  latter, 
as  measured  by  its  titration  value,  is  slightly  re- 
duced without  the  solution  of  the  iron  or  the  pro- 
duction of  any  visible  effect." 

This  bears  out  the  argument  that  oxygen  is  ab- 
sorbed by  the  metal  and  that,  being  positive  to  iron, 
its  contact  effect  is  to  render  the  iron  immune  as 
cathode  so  that  it  will  not  dissolve;  the  positive 
partner  of  the  couple  thus  formed  is  the  object  of 
the  attacks  of  the  agencies  which  cause  the  rusting 
of  iron.  As  we  have  seen,  hydrogen  in  a  free 
condition  is  "the  enemy" ;  the  inhibitory  effect  is 
therefore  destroyed  by  the  union  of  the  attacking 
hydrogen  ions  to  the  oxygen  in  the  surface  of  the 
treated  iron.  When  hydrogen  has  combined  with 
all  the  oxygen  the  iron  has  lost  its  passivity  and 
rusting  proceeds. 

9.  "In  order  to  show  beyond  doubt  that  an  oxy- 
gen electrode  is  formed  by  immersing  iron  in  a 
strong  solution  of  bichromate,  the  following  ex- 
periment was  made :  Two  polished  steel  electrodes 
were  prepared  and  chromated  by  immersion  for  a 
number  of  hours  in  a  strong  solution  of  potassium 
bichromate.  The  prepared  electrodes  were  then 
thrust  tightly  through  a  rubber  stopper  which 
closed  a  flask  which  was  then  filled  with  pure 
freshly  boiled  distilled  water.  The  electrodes  were 
then  attached  to  the  poles  of  a  primary  battery  of 
about  2  volts  potential  At  the  end  of  half  an 


100    THE  CORROSION  OF  IRON  AND  STEEL 

hour,  although  the  potential  was  not  sufficient  to 
disengage  bubbles  of  gas  and  no  visible  change  had 
occurred,  the  electrode  which  was  connected  to  the 
zinc  pole  of  the  battery  had  lost  its  passivity,  the 
other  retaining  it." 

Rapid  depolarization  had  thus  been  effected  by  a 
reversal  of  current;  under  ordinary  circumstances 
slow  depolarization,  which  finally  does  away  with 
the  benefits  of  the  treatment,  is  brought  about  by 
natural  agencies. 

Cushman's  conclusions  are  that  from  the  evi- 
dence, the  passivity  of  iron  is  best  explained  as  a 
polarization  effect  produced  by  the  separation  and 
retention  of  oxygen  on  the  surface  of  the  metal 
and  that  the  protection  afforded  by  certain  oxidiz- 
ing agents  is  electro-chemical  and  not  mechanical ; 
that  if  the  rusting  of  iron  is  due  primarily  to  the 
action  of  hydrogen  ions,  iron  in  the  condition  of 
an  oxygen  electrode  should  be  more  or  less  well 
protected  from  electrolytic  attack. 

The  corrosion  of  other  metals  may  likewise  be 
inhibited  by  treatment  with  the  bichromates  of 
sodium  and  potassium,  and  the  author  has  found 
that  galvanized  work  treated  in  this  manner  would 
retain  its  color  and  be  improved  in  quality. 

Inhibitory  treatments  are  valuable  for  applica- 
tion in  connection  with  various  shop  processes,  but 
they  offer  no  permanent  solution  to  the  problem 
of  protecting  iron  and  steel  against  corrosion.  The 
improvement  of  the  quality  of  the  metals  them- 
selves and  proper  treatment  of  their  surface,  both 


THE  INHIBITION  OF  RUSTING  101 

mechanically  or  by  the  incorporation  of  other  metals 
previous  to  coating  with  paints  or  malleable  metal 
deposits,  would  seem  to  constitute  the  most  prom- 
ising fie'ld  for  research. 


REFERENCES 

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3  The  Electrician,  Apr.  24,  1908,  p.  67. 

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8  Bull.   No.   30,  U.   S.  Bur.  Agric.,  July  23,    1907. 
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10  Loc.   Cit. 

11  Stahl  und  Eisen,  vol.  28   (1907),  p.  1564. 

12  Deuts.   Chem.  Gesell.,  vol.    18    (1881). 

13  Cushman,   Loc.   Cit.   p.    15. 

14  Trans.    Am.    El.    Chem.    Soc.    1908,    p.    175. 

15  Bull.  Soc.  Intle.   Electr.,  vol.   3   (1881),  No.  29,  p.  230. 

16  Cushman:   Loc.   Cit.,  p.   5 — Cushman:  Loc.  Cit.,  p.   27. 

17  Phil.   Trans.    Yr.    1822,   p.    253. 

18  Jl.    Am.    Chem.    Soc.,    vol.    25    (1903),    p.    10. 

19  F.   Clowes:   Nature,   1908,  p.   560. 

20  Cushman:    Loc.    Cit.,    p.    17. 

-l  Jl.   I.  &  S.   Inst.  Yr.   1872,  p.   240. 

22  Fifth   Report,   Alloys  Research  Comm.,   Inst.   Mech.   Engrs.,   1889. 

2*  Deuts.   Chem.   Gesell,  vol.   XII    (1878),  p.    n. 

24  C.  R.  Vol.   145   (1907),  p.   1283. 

25  C.    R.,    Vol.    LXXX    (1875),    p.    319. 

26  T.  W.  Richards  &  G.  E.  Behr,  Jr.,  Zeits.  Phys.  Chem.  Mar. 

27  Mitt.    Kon.    Tech.    Versuchsanstalten,    Ber.    Yr.    1890.      SuppU   I. 

28  An.    Ch.    &  Ph.,    se   S.,    vol.,    VII,   p.    1155. 

29  An.   Phys.    Chem.   Wied.,   vol.    o.    p.    104,   and  vol.   p.    388. 

102 


REFERENCES  103 

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Transactions,    1908,    p.    175. 

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32  Stahl    u.    Eisen,  vol.    VI. 

33  Proc.    Inst.    C.    E.    Yr.    1894,   P-    356. 

34  Trans.    Am.    El-Chem.    Soc.,    1908. 

35  Preuss.  Akad.  Wiss.   Ber.,  vol.    10  (1908),  p.  210. 

36  "Effect    of   strain    on    electric    conductivity":      Trans.    Roy.    Soc. 

Edin.,    vol.    XXX    (1881),   p.   413. 

37  Jl.    Franklin   Inst.   Yr.    1883,  p.    302. 

38  Proc.    Inst.    C.    E.,   vol.    69    (1882),    p.    i. 

39  Proc.    Inst.    C.    E.,    vol.    65,    (1881),    p.    73. 

40  Metallurgie,   vol.    5    (1908),   p.    173. 

41  Discussion    of    Sang's    paper    on    "The    Corrosion    of    Iron    and 

Steel,"  Proc.   Engr.  Soc.  \V.   Penna.  vol.  24   (1909),  p.  493. 

42  Loc.    Cit. 

43  Trans.,    1908,    p.    234. 

44  C.   R.  vol.  96   (1883)   p.   195- 

45  Discussion  of   Sang's  paper,  Loc.   Cit. 

46  "Corrosion  of  iron  and  steel":   Am.   Soc.  Testg.   Mats.,   1906. 

47  Proc.    Inst.    C.    E.,   vol.    IV    (1845),   p.   323. 

48  Genie    Civil  vol.   9    (1886),   p.   247. 

49  Jl.    Franklin   Inst.,   Yr.    1875,  p.   437. 

*o  Proc.   Inst.    C.    E.,  vol.    XXIV   (1864),   FP-    i   to  37- 

51  Trans.   Inst.   Nav.  Arch.,  vol.  XIII    (1872),  p.  90. 

62  Trans.  Am.  Soc.  Mech.  Engrs.,  vol.  XVI,  p.  416. 
53  Proc.  Inst.  C.   E.,  Yr.   1840,  p.  3. 

64  Trans.   Inst.   Nav.    Arch.,  vol.    3    (1882),  p.    143. 

65  Proc.    Inst.   C.    E..  vol.   XII    (1852),  p.    229." 
58  Gesundheits-Ingenieur,    Yr.    1888,    p.    235. 

57  Loc.   Cit. 

ss  Edwin   Clark:  Proc.   Soc.   C.   E.,   Yr.    1868,  p.  554. 

69  Domestic   Engineering,  vol.   XLII    (1908),   p.   67. 

60  F.  N.  Speller,  disc,  of  Sang  paper  loc.  cit. 

81  F.    N.    Speller,    Proc.    Engr.    Soc.    W.    Penna.,    vol.    22     (1906), 

P-    474- 

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104  REFERENCES 

63  A.    Mercier:    An.    des    Mines,    Yr.    1879,    p.    234. 

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05  J.    S.    Unger;   disc,   of  Sang's  paper,  loc.  cit. 

00  Records  of   the    Pittsburgh  Testing  Laboratory. 

67  R.     Ackermann:    Dingl.    Polyt.    Jl.    vol.    246,    p.     377;    also    W. 

Parker;  Jl.   I.  &  S.  Inst.,  vol.   i    (1881),  p.  39. 
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69  Progressive  Age  vol.   26,  p.    137. 

70  G.    T.    Moody,    Chem.    Soc.    Proc.   vol.    25    (1909),   p.   34. 

71  A.  Jouve,  Trans.  Faraday  Soc.   vol.   IV   (1909),  p.    156. 

72  Abel:   Proc.    Inst.    C.    E.    Yr.    1881    (Disc.    Phillip's   paper);   Rey- 

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73  Bull.    Assoc.    Beige  Chim.,    vol.    15    (7),   p.   281. 

74  Am.    Soc.   Testg.    Mats.,    1908;    also   Eng.    News,   vol.    60    (1908)? 

75  Jl.  W.  of  Scotland  I.  and  S.   Inst.,  vol.  14   (1907),  p.  82. 
70  Jl.   Franklin  Inst.,   Yr.    1908,  p.  459. 

77  Proc.  Inst.   C.  E.,  Yr.   1839,  p.  37. 

78  R.  A.  Cummings,  Disc,  of  Sang's  paper,  loc.  cit. 

79  Cushman:     Loc.  Cit.,  pp.  21   and  23. 

80  Proc.   Soc.   C.  E.,  Yr.   1868,  p.   567. 

81  Lindet:     C.  R.,  Nov.  21,  1904. 

82  C.  J.  Reed's  patent. 

83  Zts.  f.   Elektroch.,  vol.  9  (1903),  p.  454. 


GENERAL  BIBLIOGRAPHY. 

The  following  is  a  selection  of  the  more  important 
articles  on  the  Corrosion  of  Iron  and  Steel,  taken  from 
the  very  valuable  and  complete  Bibliography  of  Metal 
Corrosion  and  Protection  published  by  the  Carnegie 
Library  of  Pittsburgh.* 

The  following  abbreviations  have  been  used: 

Diag.      diagrams.  p.  page. 

Dr.         drawings.  pi.  plate. 

111.          illustrations.  v.  volume. 

n.  d.       no  date.  w.  words. 

n.  s.       new  series. 

GENERAL. 
Adie,  R. 

On  the  corrosion  of  metals.  10  p.  1845.  (In  Min- 
utes of  Proceedings  of  the  Institution  of  Civil  Engi- 
neers, v.  4,  p.  323.) 

Shows  that  saturated  salt  solutions  are  a  great  protection  from 
corrosion. 

Akerman,  R. 

Ueber  das  rosten  des  eisens.  4,200  w.  1882.  (In 
Stahl  und  Eisen,  v.  2,  p.  417.) 

Considers  theory  of  rusting,  especially  of  protective  metal  coat- 
ings, and  of  the  influence  of  manganese  in  the  rusting  of  steel. 

Alford,  H.  Carroll. 

Corrosion  of  iron  and  its  prevention.  2,200  w.  1901. 
(In  Proceedings  of  the  St.  Louis  Railway  Club,  v.  5, 
April  12,  p.  9.) 

Theory  of  rust  formation  and  preventive  measures. 

American    Society    for    Testing    Materials.      1,800    w. 
1906.     (In  Iron  Age,  v.  77,  p.  2057.) 

Abstracts  of  papers  at  ninth  annual  meeting  of  the  society; 
corrosion  of  tube  steel,  corrosion  of  wire  fencing,  electrolysis  in 
structural  steel,  etc. 

Andes,  Louis  Edgar. 

Der  eisenrost;  seine  bildung,  gefahren  und  ver- 
hiitung  unter  besonderer  beriicksichtigung  der  ver- 
wendung  des  eisens  als  bau-  und  constructionsmaterial. 
292  p.  111.  1898. 

Treats  very  fully  of  rust  formation  and  gives  many  methods  of 
prevention,  chiefly  by  preservative  paints. 

*  57  PP-.  price  10  cts.,   postpaid. 
105 


100  BIBLIOGRAPHY 

Calvert,  F.  Grace. 

Experiments  on  the  oxidation  of  iron.  1,000  w. 
1871.  (In  Chemical  News,  y.  23,  p.  98.) 

Paper  before  the  Manchester  Literary  and  Philosophical  Society. 
Indicates  that  "carbonic  acid  is  the  agent  which  determines  the 
oxidation  of  iron." 

Corrosion  of  iron.    4,700  w.     1907.     (In  Electrochemical 
and  Metallurgical  Industry,  v.  5,  p.  363.) 

Gives  in  condensed   form  papers  by  Walker  and  Cushman. 
See  also  editorial,  p.  343. 

Cranfield,  W. 

Iron;  its  oxidation,  corrosion,  protection.  7,000  w. 
1909.  (In  Journal  of  Gas  Lighting,  v.  106,  p.  443.) 

Paper  before  the  Yorkshire  Junior  Gas  Association. 
Discusses    theory,    corrosive   agents   and   the    preservative   values 
of  various  coatings. 

Crowe,  Edward. 

Corrosion  of  iron  and  steel.  2,600  w.  Dr.  1909. 
(In  Proceedings  of  the  Cleveland  Institution  of  Engi- 
neers, session  of  1908-09,  p.  148.) 

The  same,  condensed.  1,200  w.  (In  Iron  and  Coal 
Trades  Review,  v.  78,  p.  341.) 

Discussion. 

Does  not  enter  into  the  theory  of  corrosion,  but  describes  spe- 
cial instances  and  suggests  causes  and  methods  of  prevention. 

Cushman,  Allerton,  S. 

Corrosion  of  iron.     35  p.     Dr.  ill.     1907.     (In  United 

States— Office  of  Public  Roads.     Bulletin  No.  30.) 
The  same.    (In  Chemical  News,  v.  99,  p.  8,  14.) 
The   same,    condensed.      4,400    w.     (In    Iron    Age,   v. 

80,  p.  370.) 

See  also  editorial,   p.   995. 

The  same,  condensed.  5,500  w.  (In  Scientific  Amer- 
ican Supplement,  v.  64,  p.  151.) 

Abundant   references   to   original    sources. 

Describes  and  illustrates  experiments  of  the  author  tending  to 
establish  the  electrolytic  theory  of  corrosion.  Author's  own  belief 
is  that  "the  whole  subject  ...  is  an  electrochemical  one, 
which  can  be  readily  explained  under  the  modern  theory  of 
solutions." 

Corrosion  of  iron.  18  p.  Dr.  ill.  1907.  (In  Pro- 
ceedings of  the  American  Society  for  Testing  Mate- 
rials, v.  7,  p.  211.) 

Corrosion  of  steel.  4,000  w.  1908.  (In  Journal  of 
the  Franklin  Institute,  v.  165.  p.  111. 

Preservation  of  iron  and  steel.  11,000  w.  111.  1909. 
(In  Iron  and  Coal  Trades  Review,  v.  78,  p.  735.) 

The  same.     (In  Engineering,  v.  87,  p.  710,  742.) 


BIBLIOGRAPHY  107 

The  same,  slightly  condensed.  (In  Engineer,  Lon- 
don, v.  107,  p.  537,  565.) 

The  same,  slightly  condensed.  (In  Ironmonger,  v. 
127,  p.  14.) 

Paper  before  the  Iron  and  Steel  Institute. 

Consideration  of  the  nature  and  degree  of  protection  to  metals 
by  metallic  coatings,  paints  and  cement,  with  applications  of  the 
electrochemical  theory. 

Friend,  J.   Xewton. 

Rusting  of  iron.  28  p.  Dr.  1908.  (In  Journal  of 
the  Iron  and  Steel  Institute,  v.  77,  p.  5.) 

Experimental  results  indicate  that  "the  rusting  of  iron  is  pri- 
marily the  result  of  acid  attack"  rather  than  of  electrochemical 
nature  and  that  the  hygroscopic  nature  of  rust  underlies  its  cor- 
rosive action. 

Gee,  W.  W.  Haldane. 

Electrolytic  corrosion.  6,500  w.  Diag.  dr.  1908. 
(In  Electrician,  London,  v.  61.  pp.  66,  98.) 

The  same,  condensed.  4.500  w.  (In  Electrical  Engi- 
neering, London,  v.  3,  p.  559.) 

The  same,  condensed.  1.300  \v.  (In  Electrical 
Review,  London,  v.  62,  p.  692.) 

Paper  before  the  Manchester  local  section  of  the  Institution 
of  Electrical  Engineers. 

Notes  on  conditions  under  which  corrosion  takes  place. 

Hambuechen,  Carl. 

Experimental  study  of  the  corrosion  of  iron  under 
different  conditions.  40  p.  Diag.  ill.  1900.  (In  Bul- 
letin of  the  University  of  Wisconsin;  engineering 
series,  v.  2,  no.  8.) 

"Bibliography,"  p.   274. 

Concludes  that  character  and  rapidity  of  corrosion  depend 
upon  physical  and  chemical  properties  of  the  object  and  that  "the 
application  of  stress  to  metals  causes  an  increase  in  chemical 
activity." 

Heyn,  E.  &  Bauer,  O. 

Ueber  den  angriff  des  eisens  durch  wasser  und  was- 
serige  losungen.  104  p.  Folding  pi.  1908.  (In  Mit- 
teilungen  aus  dem  Koniglichen  Materialpriifungsamt, 
v.  26,  p.  1.) 

The  same,  condensed.  4,800  w.  (In  Stahl  und  Eisen, 
v.  28,  p.  1564.) 

The  same,  abstract  translation.  400  w.  (In  Journal  of 
the  Iron  and  Steel  Institute,  v.  78,  p.  663.) 

Experiments  to  determine  the  cause  of  corrosion,  the  neces- 
sary active  agents,  the  influence  of  contact  of  iron  with  other 
metals,  comparative  corrosion  of  irons  of  different  compositions 
and  the  comparative  attack  of  various  liquids  on  iron. 


108  BIBLIOGRAPHY 

Howe,  Henry  M. 

Corrosion  of  iron.  11  p.  1895.  (In  his  Metallurgy 
of  Steel,  ed.  4,  v.  1,  p.  94.) 

Considers  influence  of  surrounding  conditions  and  of  chemical 
composition,  and  the  relative  values  of  protective  coatings. 

Lindsay,  Charles  C. 

On  the  corrosion  and  preservation  of  iron  and  steel. 
32  p.  Dr.  1881.  (In  Transactions  of  the  Institution 
of  Engineers  and  Shipbuilders  in  Scotland,  v.  24,  p.  77.) 

The  same,  condensed.  2,000  w.  (In  Scientific  Amer- 
ican Supplement,  v.  12,  p.  4570.) 

Consideration  of  the  cause  and  action  of  corrosion  and  methods 
for  its  prevention  by  coatings  of  paint,  metal  or  magnetic  oxid. 

Mallet,  Robert. 

First  report  upon  experiments,  instituted  at  the 
request  of  the  British  Association,  upon  the  action  of 
sea  and  river  waters,  whether  clear  or  foul,  and  at 
various  temperatures,  upon  cast  and  wrought  iron.  59 
p.  1839.  (In  Report  of  the  eighth  meeting  of  the 
British  Association  for  the  Advancement  of  Science, 
p.  253.) 

Summary  of  knowledge  of  the  subject  to  that  time  (1839),  in- 
dicating directions  in  which  further  investigation  was  necessary. 

Second  report  upon  the  action  of  air  and  water, 
whether  fresh  or  salt,  clear  or  foul,  and  at  various 
temperatures,  upon  cast  iron,  wrought  iron,  and  steel. 
88  p.  1840.  (In  Report  of  the  tenth  meeting  of  the 
British  Association  for  the  Advancement  of  Science, 
p.  221.) 

Experiments  on  the  relative  rates  of  corrosion  of  different 
irons  in  fresh  and  salt  water  and  the  protection  of  iron  and  steel 
by  coatings  of  paint  or  metal. 

Third  report  upon  the  action  of  air  and  water, 
whether  fresh  or  salt,  clear  or  foul,  and  at  various  tem- 
peratures, upon  cast  iron,  wrought  iron,  and  steel.  53 
p.  1843.  (In  Report  of  the  thirteenth  meeting  of  the 
British  Association  for  the  Advancement  of  Science, 
P-  1.) 
Mason,  F.  H. 

Rusting  of  iron.  1,200  w.  1908.  (In  Mining  and 
Scientific  Press,  v.  97,  p.  329. 

Comments  on  conclusions  of  Tilden  and  describes  original  ex- 
periments in  which  potassium  bichromate  was  found  to  retard 
corrosion. 

Mugdan,  M. 

Ueber   das   rosten   des   eisens   und   seine   passivitat. 


BIBLIOGRAPHY  109 

7,000  w.     1903.     (In  Zeitschrift  fiir  elektrochemie,  v.  9, 
p.  442.) 

The  same,  abstract.  250  \v.  (In  Journal  of  the  Iron 
and  Steel  Institute,  v.  64,  p.  720.) 

Finds  that  rust  forms  more  readily  in  solutions  of  nitrate, 
chlorid,  sulphate  and  perchlorate. 

Newman,  John. 

Metallic  structures;  corrosion  and  fouling  and  their 
prevention;  a  practical  aid-book  to  the  safety  of  works 
in  iron  and  steel,  and  of  ships,  and  to  the  selection 
of  paints  for  them.  374  p.  1896. 

Record  of  author's  experience,  supplemented  by  information 
compiled  from  many  sources.  Omits  electrolysis,  but  considers 
nearly  all  other  causes  of  corrosion. 

Sang,  Alfred. 

Corrosion  of  iron  and  steel.  49  p.  1909.  (In  Pro- 
ceedings of  the  Engineers'  Society  of  Western  Penn- 
sylvania, v.  24,  p.  493.)  , 

Discussion,  21  p. 

Comprehensive  treatment  of  the  subject,  tracing  the  develop- 
ment of  the  theory  of  corrosion  and  methods  for  its  prevention. 
References  given  in  full. 

Sexton,  A.  Humboldt. 

Corrosion  and  protection  of  metals.     147  p.     1906? 

Treats  of  corrosion  of  iron,  steel,  lead,  zinc,  copper,  etc.,  and 
protection  both  by  paints  and  metallic  coatings. 

"Useful  and  generally  accurate   summary  of  present  knowledge." 
Reviciv.     1,000  w.     (In  Engineering  News,  v.  56,  p. 
184.) 
Stoughton,  Bradley. 

Corrosion  of  iron  and  steel.  15  p.  111.  1908.  (In 
his  -Metallurgy  of  Iron  and  Steel,  p.  422.) 

"References  on  corrosion,"  p.  436. 

Thurston,  Robert  H. 

Properties  of  iron  and  steel.  2,500  w.  1901.  (In 
his  Materials  of  Engineering,  ed.  8,  revised,  pt.  2,  p. 
328.) 

The  same.  1,200  w.  1885.  (In  his  Text-book  of  the 
Materials  of  Construction,  p.  210.) 

Discusses  corrosion,  durability  and  preservation  of  iron  and  steel. 

Thwaite,  Benjamin  Howard. 

Coefficients  of  corrosion  of  iron  and  steel.  400  w. 
1880.  (In  Journal  of  the  Iron  and  Steel  Institute,  v. 
17,  p.  667.) 

Abstract  of  paper  showing  effects  of  corrosion  under  various 
conditions.  Shows  danger  of  contact  of  different  metals. 

Turner,   Thomas. 

Corrosion  of  iron  and  steel.  20  p.  1908.  (In  his 
Metallurgy  of  Iron,  ed.  3,  p.  413.) 


110  BIBLIOGRAPHY 

Review  of  old  and  new  theories  and  methods  of  prevention, 
with  abundant  references  to  other  works. 

Walker,  William  H. 

Corrosion  of  iron  and  steel,  and  modern  methods  of 
preventing  it.  3,000  w.  1909.  (In  Engineering  Rec- 
ord, v.  59,  p.  222.) 

Abstract  of  paper  before  the  Boston  Society  of  Arts. 
Considers     theory     of     prevention,     and     satisfactory     conditions 
attainable. 

CHEMICAL.     PHYSICAL.     THEORETICAL. 

Andrews,  Thomas. 

Effect   of   stress  on   the   corrosion   of  metals.     6,000 
w.     111.     1894.    (In  Minutes  of  Proceedings  of  the  Insti- 
tution of  Civil  Engineers,  v.   118,  p.  356.) 
Brown,  A.  Cruin. 

On  the  chemical  processes  involved  in  the  rusting 
of  iron.  1,200  w.  1888.  (In  Journal  of  the  Iron  and 
Steel  Institute,  v.  33,  p.  129.) 

Discussion,   800   w. 

Rusting  caused  by  action  of  carbon  dioxid  and  oxygen. 

Burgess,  Charles  F. 

Corrosion  of  iron  from  the  electrochemical  stand- 
point. 32  p.  Diag.  dr.  ill.  1908.  (In  Transactions  of 
the  American  Electrochemical  Society,  v.  13,  p.  17.) 

Discussion,   6  p. 

The  same,  without  discussion.  (In  Electrical  Review, 
New  York,  v.  53,  p.  371,  436.) 

Considers  the  influence  of  strain  and  of  inequalities  of  tem- 
perature on  corrosion. 

Cribb,  Cecil  H.  &  Arnaud,  F.  W.  F. 

On  the  action  of  slightly  alkaline  waters  on  iron. 
5,600  w.  111.  1905.  (In  Analyst,  v-  30,  p.  225.) 

The  same,  condensed.     (In  Engineering,  v.  81,  p.  32.) 

Experiments  indicate  increased  corrosion  in  alkaline  solution, 
though  less  rapid  in  boilers  than  under  ordinary  conditions. 

Cushman,  Allerton  S. 

Electrolytic  theory  of  the  corrosion  of  iron.  2,200 
w.  1907.  (In  Transactions  of  the  American  Electro- 
chemical Society,  v.  12,  p.  403.) 

Discussion,  600  w. 

The  same  (In  Electrical  Engineer,  London,  v.  47, 
p.  701.) 

Electrolysis  and  corrosion.  3,800  w.  1908.  (In  Pro- 
ceedings of  the  American  Society  for  Testing  Mate- 
rials, v.  8,  p.  238.) 

The  same.     (In  Engineering  Record,  y.  58,  p.  349.) 

Discussion  of  electrolytic  corrosion  and  its  physico-chemical 
explanation. 


BIBLIOGRAPHY  111 

Davis,  R.  O.  E. 

Corrosion  of  iron.  900  w.  1907.  (In  Chemical 
Engineer,  v.  5,  p.  174.) 

Experiments  indicate  that  water  and  oxygen  are  the  only  essen- 
tials for  corrosion. 

Dunstan,  Wyndham  Rowland,  and  others. 

Rusting  of  iron.  26  p.  Dr.  1905.  (In  Journal  of 
the  Chemical  Society,  v.  87,  pt.  2,  p.  1548.) 

Claims  proof  that  for  the  rusting  of  iron  the  presence  of 
oxygen  and  water  only  is  necessary  and  that  "in  the  ordinary 
atmospheric  rusting  of  pure  iron  electrolytic  action  does  not  occur." 

Freund,  Martin. 

Ueber  eine  eigenartige  zerstorung  von  wasserlei- 
tungsrohren.  2,800  w.  1904.  (In  Zeitschrift  fur  ange- 
wandte  Chemie,  v.  17,  pt.  1,  p.  45.) 

Investigation  of  a  destructively  corroded  cast-iron  water-pipe, 
giving  analyses  of  original  metal  and  of  the  corroded  portions. 

Gore,  G. 

Influence  of  ordinary  chemical  corrosion  [on  voltaic 
action].  5  p.  n.  d.  (In  his  Art  of  Electrolytic  Separa- 
tion of  Metals,  p.  65.) 

Considers  influence  of  kind  of  substance  on  chemical  corro- 
sion, influence  of  temperature  on  corrosion  and  includes  table 
showing  corrosion  series  of  the  metals  at  60°  F.  and  160°  F. 

Some  relations  of  heat  to  voltaic  and  thermo-elec- 
tric action  of  metals  in  electrolytes.  2,800  w.  1883. 
(In  Proceedings  of  the  Royal  Society  of  London,  v.  36, 
p.  50.) 

Abstract.  Many  experiments  tended  to  show  that  "the  most 
chemically-positive  metals  were  usually  the  most  quickly  corroded, 
and  the  corrosion  .  .  .  was  usually  the  fastest  with  the  most 
acid  solutions.  .  .  .  Corrosion  was  not  the  cause  of  pure  thermo- 
electric action  of  metals  in  liquids. 

Some  relations  of  heat  to  voltaic  and  thermo-elec- 
tric action  of  metals  in  electrolytes.  40  p.  111.  1883. 
(In  Proceedings  of  the  Royal  Society  of  London,  v. 
37,  p.  251.) 

Examines  "the  relations  of  the  thermo-electric  to  the  chemico- 
electric  behaviour  of  metals  in  electrolytes,  and  to  ordinary  chem- 
ical corrosion,  and  the  source  of  voltaic  currents." 

On  some  relations  of  chemical  corrosion  to  voltaic 
current.  10  p.  1884.  (In  Proceedings  of  the  Royal 
Society  of  London,  v.  36,  p.  331.) 

"Chief  object  of  this  research  was  to  ascertain  the  amounts  of 
voltaic  current  produced  by  the  chemical  corrosion  of  known 
weights  of  various  metals  in  different  liquids." 

Lodin. 

Sur  les  causes  d'alteration  interieure  des  chaudieres 


112  BIBLIOGRAPHY 

a    vapeur.      600    w.       1880.      (In    Comptes    rendus    des 
seances  de  1'Academie  des  sciences,  v.  91,  p.  217.) 

Chief  cause  is  oxidation  due  to  oxygen  set  free  during  decom- 
position of  water. 

Milton,  James  Tayler. 

Corrosion  and  decay  of  metals.  5,000  w.  Dr.  1908. 
(In  Mechanical  Engineer,  v.  22,  p.  530,  580.) 

Lecture   before  the   Institute  of  Marine  Engineers. 

Explanation  of  theory  of  corrosion,  with  examples.  Considers 
corrosion  as  due  to  the  action  of  a  liquid  or  agent  in  such  a  way 
that  the  current  leaves  the  metal  to  enter  the  corrosive  agent. 

Moody,  Gerald  Tattersall. 

Rusting  of  iron.  3,300  w.  Dr.  1906.  (In  Journal 
of  the  Chemical  Society,  v.  89,  pt.  1,  p.  720.) 

Challenges  Dunstan's  conclusions  and  asserts  that  carbonic 
acid  must  be  present,  in  however  minute  quantity,  before  rusting 
begins. 

Pennock,  J.  D.  &  Morton,  D.  A. 

Commercial  aqua  ammonia;  its  effect  upon  iron, 
its  impurities,  and  methods  for  determining  them. 
3,500  w.  1902.  (In  Journal  of  the  American  Chemi- 
cal Society,  v.  24,  p.  377.) 

Concludes  that  concentrated  ammonia  solutions  not  only  do  not 
rust  clean  iron,  but  prevent  its  rusting  in  the  presence  of  corrosive 
agents. 

Richards,  Theodore  William,  &  Behr,  G.  E.,  Jr. 

Electromotive  force  of  iron  under  varying  condi- 
tions, and  the  effect  of  occluded  hydrogen.  43  p. 
Diag.  dr.  1906. 

Takes  issue  (p.  20)  with  conclusion  that  corrosion  is  neces- 
sarily increased  by  stress. 

Rusting   of  iron.     1906-07.      (In    Nature,  v.   74,  p.  540, 
564,  586,  610;  v.  75,  p.  31,  390,  438,  461.) 

Letters  by  Friend,  Moody,  Richardson,  Meehan,  Dunstan  and 
Stromeyer  concerning  the  theory  of  rusting  and  the  action  of 
carbon  dioxid. 

Schleicher,  A.  &  Schultz,  G. 

Untersuchungen  iiber  das  rosten  von  eisen.  2,400 
w.  Diag.  1908.  (In  Stahl  und  Eisen,  v.  28,  p.  50.) 

Experiments  on  the  differences  of  potential  of  metal  plates 
separated  from  one  another  in  water. 

Tilden,  William  Augustus. 

Rusting  of  iron.  3,500  w.  Dr.  1908.  (In  Journal 
of  the  Chemical  Society,  v.  93,  p.  1356.) 

Shows  that  carbonic  acid  is  not  necessary  to  corrosion,  but 
that  it  hastens  the  action  and  that  rusting  is  due  initially  to 
electrolytic  action,  resulting  in  the  production  of  ferrous  hydroxid 
or  carbonate. 


BIBLIOGRAPHY  113 

Traube,  Moritz. 

Ueber  die  mitwirkung  des  wassers  bei  der  langsamen 
verbrennung  des  zinks,  bleis,  eisens  und  palladiumwas- 
serstoffs.  3,400  w.  1885.  (In  Berichte  der  Deutschen 
Chemischen  Gesellschaft,  v.  18,  pt.  2,  p.  1877.) 

Author's  theory  is  that  in  slow  oxidation  of  metals  water  is 
decomposed  with  formation  of  hydrogen  peroxid  and  that  nascent 
pxygen  cannot  be  formed  simultaneously. 

Walker,  William  H.  and  others. 

Corrosion  of  iron  and  steel.  5,600  w.  1907.  (In 
Journal  of  the  American  Chemical  Society,  v.  29,  1251; 
v.  30,  p.  473.) 

The  same.     (In  Chemical  News,  v.  97,  p.  31,  40.) 

Indicates  that  iron  dissolves  in  water  in  the  absence  of  both 
parbon  dioxid  and  oxygen  and  that  on  the  surface  of  iron  exposed 
to  corrosion  there  is  a  marked  difference  in  potential  on  different 
areas.  , 

Walker,  William  H. 

Electrolytic  theory  of  the  corrosion  of  iron  and  its 
applications.  4,000  w.  111.  1909.  (In  Iron  and  Coal 
Trades  Review,  v.  78,  p.  749.) 

The  same.    (In  Engineering,  v.  87,  p.  708.) 

The  same.     (In  Mechanical  Engineer,  v.  23,  p.  677.) 

The  same,  condensed.  1,100  w.  (In  Ironmonger,  v. 
127,  p.  13.) 

Paper  before  the  Iron  and  Steel  Institute. 

Function  of  oxygen  in  the  corrosion  of  metals. 
5?000  w.  1908.  (In  Transactions  of  the  American 
Electrochemical  Society,  v.  14,  p.  175.) 

The  same,  condensed.  1,700  w.  (In  Electrochemi- 
cal and  Metallurgical  Industry,  v.  7,  p.  150.) 

Considers  the  corrosion  of  zinc-plated  iron  wire  and  of  tubes 
and  shells  of  steam-boilers. 

Protection  of  iron  and  steel  from  corrosion.  6,000 
w.  111.  1909.  (In  Engineering  Magazine,  v.  37,  p.  198.) 

Treats  of  the  ionic  nature  of  corrosion  and  the  method  of 
observing  its  progress  and  location  by  means  of  indicators. 

Walker,  William  H.  &  Dill,  Colby. 

Effect  of  stress  upon  the  electromotive  force  of 
soft  iron.  4,600  w.  Diag.  dr.,  1907.  (In  Transactions 
of  the  American  Electrochemical  Society,  v.  li,  p.  153.) 

The  same,  condensed.  1,800  w.  (In  Electrochemical 
and  Metallurgical  Industry,  v.  5,  p.  270.) 

See  also  editorial,  p.   254. 

Experimental  results  tend  to  show  that  differences  of  potential 
are  not  necessarily  the  result  of  stress. 


114  BIBLIOGRAPHY 

Influence  of  stress  upon  the  corrosion  of  iron.  3,100 
w.  Diag.  1907.  (In  Proceedings  of  the  American 
Society  for  Testing  Materials,  v.  7,  p.  229.) 

Discussion,  500  w. 

Whitney,  W.  R. 

Corrosion  of  iron.  5,000  w.  Dr.  1903.  (In  Journal 
of  the  American  Chemical  Society,  v.  25,  pt.  1,  p.  394.) 

Emphasizes  fact  that  the  effect  of  carbonic  acid  on  corrosion 
is  cyclic  and  that  under  favoring  conditions  "even  a  trace  of  car- 
bonic acid  may  dissolve  an  unlimited  quantity  of  iron." 

EFFECT  OF  IMPURITIES. 

Bauer,  O. 

Ueber  den  einflus  der  reihenfolge  von  zusatzen  zttm 
flusseisen  auf  die  widerstandsfahigkeit  gegen  verdiinnte 
schwefelsaure.  1,000  w.  Diag.  dr.  1905.  (In  Mitteil- 
ungen  aus  dem  Koniglichen  Materialpriifungsamt,  v. 
23,  p.  292.) 

Considers  the  influence  of  aluminium  and  tungsten  on  the 
corrosion  of  steel  in  dilute  sulphuric  acid. 

Breuil,  Pierre. 

Corrosion  tests  on  copper  steels.  400  w.  Dr.  1907. 
(In  Journal  of  the.  Iron  and  Steel  Institute,  v.  74, 
p.  41.) 

Experiments  using  sulphuric  acid  as  corrosive  liquid  "make 
copper  steels  rank  in  value  with  nickel  steels  in  respect  of  cor- 
rosion." 

Corrosion  tests  on  the  [copper]  steels  as  rolled. 
1,200  w.  1907.  (In  Journal  of  the  Iron  and  Steel  Insti- 
tute, v.  74,  p.  60.) 

Tests  show  corrosion  to  take  place  much  more  slowly  with 
rolled  steel. 

Huntly,  G.  Nevill. 

Sulphur  as  a  cause  of  corrosion  in  steel.  1,600  w. 
1909.  (In  Journal  of  the  Society  of  Chemical  Indus- 
try, v.  28,  p.  339.) 

Considers  action  resulting  from  the  solution  of  the  sulphur 
present  as  sulphid  in  the  boiler  metal. 

Williams,  F.  H. 

Influence  of  copper  in  retarding  corrosion  of  soft 
steel  and  wrought  iron.  400  w.  1900.  (In  Proceed- 
ings of  the  Engineers'  Society  of  Western  Pennsyl- 
vania, v.  16,  p.  231.) 

Indicates  that  presence  of  copper  retards  corrosion. 

Yarrow,  A.  F. 

Some  experiments  having  reference  to  the  durabil- 
ity of  water-tube  boilers.  2,600  w.  1899.  (In  Transac- 


BIBLIOGRAPHY  115 

tions  of  the  Institution  of  Naval  Architects,  v.  41,  p. 
333.) 

Discussion. 

From  experimental  results  assumes  that  both  from  acid  corro- 
sion and  from  the  action  of  steam  nickel  steel  boiler-tubes  will  be 
far  more  durable  than  those  of  mild  steel. 

ACID  TESTS. 
Burgess,  Charles  F.  &  Engle,  S.  G. 

Observations  on  the  corrosion  of  iron  by  acids. 
3,000  w.  1906.  (In  Transactions  of  the  American 
Electrochemical  Society,  v.  9.  p.  199.) 

Effect  of  normal  solutions  of  sulphuric  and  hydrochloric  acids 
on  electrolytic  iron. 

Report  of  committee  U  on  the  corrosion  of  iron  and 
steel.  700  w.  1907.  (In  Proceedings  of  the  American 
Society  for  Testing  Materials,  v.  7,  p.  209.) 

Offers  suggestions  as  to  the  conditions  for  experiments  on  the 
connection  between  the  rapidity  of  solution  in  acid  and  natural 
corrosion. 

Report  of  committee  U  on  the  corrosion  of  iron  and 
steel.  2,000  w.  Diag.  1908.  (In  Proceedings  of  the 
American  Society  for  Testing  Materials,  v.  8,  p.  231.) 
Contains  opecifications  for  tests  of  steel  wire  and  remarks  on 
the  value  of  acid  and  immersion  tests  in  determining  resistance  to 
corrosion. 

RELATIVE  CORROSIONS. 
Fraser,  Alexander  G. 

Relative  rates  of  corrosion  of  acid  and  basic  steel. 
16  p.  Folding  pi.  1907.  (In  Journal  of  the  West  of 
Scotland  Iron  and  Steel  Institute,  v.  14,  p.  82.) 

Discussion,  p.   112.     20  p. 

The  same,  condensed.  1,600  w.  (In  Iron  Age,  v. 
79,  p.  1196.) 

Tests  in  air,   river  water,  salt  water  and  sulphuric  acid. 

Howe,  Henry  M. 

Relative  corrosion  of  wrought  iron  and  steel.  5,600 
w.  1895.  (In  Mineral  Industry,  v.  4,  p.  429.) 

The  same,  condensed.  1,600  w.  (In  Journal  of  the 
Iron  and  Steel  Institute,  v.  50,  p.  427.) 

Gives  results  both  from  laboratory  experiments  and  from  actual 
industrial  use. 

Relative  corrosion  of  wrought  iron,  soft  steel  and 
nickel  steel.  1,500  w.  Dr.  1900.  (In  Engineering  and 
Mining  Journal,  v.  70,  p.  188.) 

Relative  corrosion  of  wrought  iron  and  steel.  1,800 
w.  Dr.  1906.  (In  Proceedings  of  the  American  Soci- 
ety for  Testing  Materials,  v.  6,  p.  155.) 

Discussion,   7,000   w. 


116  BIBLIOGRAPHY 

The  same,  condensed.  1,300  w.  (In  American 
Machinist,  v.  29,  p.  49.) 

The  same,  condensed.  (In  Engineering  Magazine,  v. 
31,  p.  750.) 

The  same,  condensed.  (In  Industrial  World,  v.  40,  p. 
228.) 

The  same,  condensed.      (In  Iron  Age,  v.  77,  p.  2047.) 

Rapid  corrosion  of  steel  in  many  instances  may  be  due  to  the 
inferior  quality  of  the  steel. 

Gruner. 

Recherches  sur  1'oxydabilite  relative  des  fontes,  des 
aciers  et  des  fers  doux.     1,000  w.     1883.     (In  Comptes 
rendus  des  Seances  de  1'Academie  des  Sciences,  v.  96, 
p.  195.) 
Kosmann,  B. 

Ueber  die  corrosion  von  fluss^  und  schweisseisen 
und  iiber  den  zerfall  von  legirungen.  2,100  w.  1893. 
(In  Stahl  und  Eisen,  v.  13,  pt.  1,  p.  149.) 

The  same,  condensed.  (In  Journal  of  the  Iron  and 
Steel  Institute,  v.  43,  p.  399.) 

Difference  in  resistance  to  corrosion  of  ingot  and  weld  is  held 
to  be  due  entirely  to  difference  in  their  chemical  composition. 

Parker,  William. 

On  the  relative  corrosion  of  iron  and  steel.  11,200 
w.  Dr.  1881.  (In  Journal  of  the  Iron  and  Steel  Insti- 
tute, v.  18,  p.  39.) 

Effects  of  exposure  in  air,  in  sea-water,  in  marine  boilers,  etc. 

Fillips,  David. 

On  the  comparative  endurance  of  iron  and  mild 
steel  when  exposed  to  corrosive  influences.  25  p.  Dr. 
1881.  (In  Minutes  of  Proceedings  of  the  Institution  of 
Civil  Engineers,  v.  65,  p.  73.) 

Discussion,  40  p. 

Considers  admiralty  tests  and  tests  by  tlie  author  indicating 
greater  resistance  to  corrosion  of  iron. 

Rudeloff,  M. 

Bericht  iiber  vergleichende  untersuchungen  von 
schweisseisen  und  flusseisen  auf  widerstand  gegen 
rosten.  125  p.  111.  1902.  (In  Mittheilungen  aus  den 
Koniglichen  Technischen  Versuchsanstalten,  v.  20,  p. 
83.) 

The  same,  condensed.  4,000  w.  (In  Stahl  und  Eisen, 
v.  23,  p.  384.) 

The  same,  abstract.  1,500  w.  (In  Journal  of  the  Iron 
and  Steel  Institute,  v.  63,  p.  713.) 

Extensive  experiments  on  the  relative  resistance  to  corrosion 
of  wrought-iron  and  steel,  considering  the  effect  of  different  condi- 


BIBLIOGRAPHY  117 

tions    and    coatings    and    giving    the    relative    corrosive    action    of 
various   agencies. 

Speller,  Frank  N. 

Puddled  iron  versus  soft  steel.  2,200  w.  111.  1905. 
(In  Iron  Age,  v.  75,  p.  1666.  1881.) 

Claims  equal  resistance  of  iron  and  steel  to  corrosion,  in  reply 
to  statements  of  Roe. 

Corrosion  of  iron  and  steel.  900  w.  1907.  (In  Pro- 
ceedings of  the  Engineers'  Society  of  Western  Penn- 
sylvania, v.  22,  p.  472.) 

The  same.     (In  Iron  Age,  v.  79,  p.  478.) 

Discussion,  1,800  w. 

Gives  results  of  tests  showing  steel  to  be  superior  to  wrought- 
iron. 

CORROSION  IX  SEA-WATER. 

Andrews,  Thomas. 

On  galvanic  action  between  wrought-iron.  cast 
metals  and  various  steels  during  long  exposure  in  sea- 
water.  5,000  w.  111.  1884.  (In  Minutes  of  Proceed- 
ings of  the  Institution  of  Civil  Engineers,  v.  77,  p.  323.) 

Corrosion  of  metals  during  long  exposure  in  sea- 
water.  7,5XX)  w.  111.  1885.  (In  Minutes  of  Proceed- 
ings of  the  Institution  of  Civil  Engineers,  v.  82,  p.  281.) 

Diegel,  H. 

Einiges  iiber  die  korrosion  der  metalle  im  seewas- 
ser.  95  p.  Folding  pi.  1903.  (In  Verhandlungen  des 
Vereins  zur  Beforderung  des  Gewerbfleisses,  v.  82,  p. 
91.) 

The  same,  condensed.  4,500  w.  (In  Zeitschrift  des 
Vereines  Deutscher  Ingenieure,  v.  47,  p.  1122.) 

The  same,  abstract.  400  w.  (In  Journal  of  the  Iron 
and  Steel  Institute,  v.  65,  p.  677.) 

Extensive  experiments  lead  author  to  claim  that  impure  metals 
do  not  corrode  in  salt  water  faster  than  pure  metals.  Foreign 
elements  introduced  were  phosphorus  and  nickel. 

Farquharson,  J. 

Corrosive  effects  of  steel  on  iron  in  salt  water. 
4,800  w.  1882.  (In  Transactions  of  the  Institution  of 
Naval  Architects,  v.  23,  p.  143.) 

Experiments  indicating  that  contact  of  iron  and  steel  should  be 
avoided. 

Discussion. 

Johnstone,  George. 

Notes  on  the  serious  deterioration  of  steel  vessels 
from  the  effects  of  corrosion.  7  p.  1901.  (In  Trans- 


118  BIBLIOGRAPHY 

actions  of  the  Institution  of  Engineers  and  Ship- 
builders in  Scotland,  v.  45,  p.  71.) 

Discussion,    28   p. 

Especially  on  corrosion  of  internal  parts  of  vessels  and  on 
vessels  in  the  tropics. 

Lidy. 

Note  sur  1'alteration  des  metaux  par  1'eau  de  mer. 
2,200  w.  111.  1897.  (In  Annales  des  ponts  et  chaus- 
sees,  memoires,  ser.  7,  v.  14,  3e  trimestre,  p.  338.) 

The  same,  condensed.  900  w.  (In  Engineering 
News,  v.  39,  p.  85.) 

Describes  condition  of  metals  after  exposure  to  the  action  of 
sea-water  for  several  hundred  years. 

Mallet,  Robert. 

On  the  corrosion  and  fouling  of  iron  ships.  60  p. 
1872.  (In  Transactions  of  the  Institution  of  Naval 
Architects,  v.  13,  p.  90.) 

Discussion,    10  p. 

"Catalogue  of  British  patent  inventions,"  p.   135,   17  p. 

Sabin,  Alvah  Horton. 

Experiments  on  the  protection  of  steel  and  alumi- 
num exposed  to  sea  water.  8,000  w.  1896.  (In  Trans- 
actions of  the  American  Society  of  Civil  Engineers,  v. 
36,  p.  483.) 

Condition  of  plates  with  various  preservative  coatings  after  six 
months'  immersion  in  sea-water. 

Discussion  and  correspondence. 

Experiments  on  the  protection  of  steel  and  alumi- 
num exposed  to  water.  5,000  w.  1899.  (In  Transac- 
tions of  the  American  Society  of  Civil  Engineers,  v. 
43,  p.  444.) 

Continuation  of  above  experiments. 
Discussion. 

The  same,  condensed.  (In  Engineering  News,  v.  40, 
p.  54.) 

PIPES. 

Committee  report  on  relative  corrosion  of  wrought 
iron  and  steel  pipes.  1,600  w.  Dr.  ill.  1909.  (In 
Plumbers'  Trade  Journal,  v.  14,  p.  214.) 

The  same,  slightly  condensed.  1,300  w.  (In  Heating 
and  Ventilating  Magazine,  v.  6,  p.  12.) 

Report  to  American  Society  of  Heating  and  Ventilating  Engi- 
neers. 

Tests  indicate  steel  pipe  of  good  quality  to  be  as  durable  as 
wrought-iron  pipe. 

Corrosion  of  pipe  in  coal  mines.  450  w.  111.  1906. 
(In  Iron  Age,  v.  78,  p.  80.) 

Results  showing  superiority  of  "Spellerized"  steel  pipes  in  the 
sulphur  water  of  coal  mines. 


BIBLIOGRAPHY  119 

Dudley,  William  L. 

Effect  of  coal  gas  on  the  corrosion  of  wrought  iron 
pipe  buried  in  the  earth.  1,100  w.  1908.  (In  Journal 
of  the  American  Chemical  Society,  v.  30,  p.  247.) 

Experiments  in  earth  saturated  with  coal  gas,  indicating  that 
amount  of  corrosion  is  determined  by  the  chlorin  content  in  the 
earth.  • 

Howe,  Freeland,   jr. 

Action  of  water  on  pipes.  5,000  w.  1908.  (In 
Journal  of  the  New  England  Water  Works  Associa- 
tion, v.  22,  p.  43.) 

Consideration  of  the  nature  of  water  and  of  iron  pipe  and  of 
the  electrolytic  action  that  takes  place. 

Howe,  Henry   M.   &  Stoughton,  Bradley. 

Relative  corrosion  of  steel  and  wrought  iron  tubing. 
20  p.  111.  1908.  (In  Proceedings  of  the  American 
Society  for  Testing  Materials,  v.  8,  p.  247.) 

Discussion,    15   p.  i 

The  same.     (In  Industrial  World,  v.  83,  p.  1244.) 

Believes  that  modern  steel  tubing  is  equal  to  wrought-iron 
tubing  and  that  the  prejudice  against  it  is  due  to  practical  experi- 
ence with  older  tubing. 

Knudson,  Adolphus  A. 

Electrolytic  corrosion  of  the  bottom  of  oil  tanks 
and  of  other  structures.  4,300  w.  Dr.  ill.  1908.  (In 
Transactions  of  the  American  Electrochemical  Society, 
v.  14,  p.  189.) 

Discussion,   900  w. 

Corrosion  of  oil-tanks  thought  to  be  caused  by  galvanic  action 
set  up  by  the  distribution  of  acid  or  alkaline  electrolytes  over  the 
iron  surface. 

McAlpine,  William  J. 

Corrosion  of  iron.  1,200  w.  1868.  (In  Transactions 
of  the  American  Society  of  Civil  Engineers,  v.  1,  p.  23.) 

Cites  instances  of  preservation  of  water-pipes,  iron  submerged 
in  salt  water,  etc. 

Mason,  William  P. 

Action  of  water  upon  metals:  tanks,  pipes,  con- 
duits, boilers,  etc.  19  p.  Dr.  1902.  (In  his  Water 
Supply,  p.  394.) 

Data  compiled  from  various  sources,  giving  references. 

Rust  in  galvanized  iron  water  service  pipe.  6,000  w. 
1909.  (In  Metal  Worker,  v.  71,  March  27,  p.  48;  April 
3,  p.  52;  April  10,  p.  45;  April  17,  p.  48;  April  24,  p.  39.) 

Continued  discussion,  by  lette'r,  in  reply  to  questions  by  editor 
concerning  the  presence  and  prevention  of  corrosion  in  water-pipe. 


120  BIBLIOGRAPHY 

Siebel,  E.  P. 

Pitting  of  iron,  particularly  pipe;  its  causes  and 
possible  preventives.  3,000  w.  111.  1909.  (In  Na- 
tional Engineer,  v.  13,  p.  192.) 

Paper  before  the  Chicago  section  of  the  Society  of  Brewing 
Technology. 

Regards  pitting  as  due  to  electrochemical  decomposition  in  the 
presence  of  water  and  dependent  upon  the  homogeneity  of  the 
material.  Wrought-iron  pipe  considered  more  durable  than  steel 
pipe. 

Speller,  Frank  N. 

Wrought  pipe-threading  and  relative  durability  of 
steel  and  iron.  3,000  w.  Dr.  ill.  1905.  (In  Journal 
of  the  Canadian  Mining  Institute,  v.  8,  p.  46.) 

The  same.     (In  Iron  Age,  v.  75,  p.  741.) 

Review  and  illustrations  of  United  States  Navy  Department 
tests  on  pitting.  Experiments  by  National  Tube  Co.,  showing  that, 
in  resistance  to  corrosion,  common  iron  and  Bessemer  steel  are 
both  slightly  superior  to  charcoal  iron. 

Stewart,  A.  W. 

Corrosion  in  metal  pipes  on  board  ship.  6,200  w. 
1903.  (In  Transactions  of  the  Institution  of  Naval 
Architects,  v.  45,  p.  183.) 

The  same,  abstract.  (In  Engineer,  London',  v.  95,  p. 
374.) 

Discussion. 

Considers  the  action  of  impurities  on  the  pipes,  especially  of 
chlorine  and  organic  impurities. 

Thomson,  T.  N. 

Relative  corrosion  of  wrought  iron  and  soft  steel 
pipes.  2,800  w.  Dr.  ill.  1908.  (In  Heating  and  Venti- 
lating Magazine,  v.  5,  p.  15.) 

The  same,  slightly  condensed.  2,500  w.  (In  Iron 
Age,  v.  81,  p.  434.) 

See  also  letter  by  G.   Schuhmann,  p.   520. 

Paper  before  the  American  Society  of  Heating  and  Ventilating 
Engineers. 

Conclusion  from  experiments  is  that  "plain  steel  pipe  is  more 
durable  than  plain  wrought-iron  pipe  when  used  to  convey  hot 
water  and  subject  only  to  internal  corrosion." 

Wrought-iron  pipe  versus  steel  pipe.  1,300  w.  Dr. 
1908.  (In  Heating  and  Ventilating  Magazine,  v.  5, 
p.  8) 

Contains  extracts  from  a  pamphlet  published  by  the  Reading 
Iron  Co.,  claiming  that  wrought-iron  is  the  more  durable. 

BOILERS. 
Baucke,  H. 

Beitrag  zur  metallographie  des  flusseisens.  1,600 
w.  111.  1899.  (In  Baumaterialienkunde,  v.  4,  p.  349.) 


BIBLIOGRAPHY  121 

The  same,  in  French.      (In  Baumaterialienkunde,  v. 

4,  p.  349.) 

The  same.     (In'  Stahl  und  Eisen,  v.  20,  pt.  1,  p.  260.) 
The  same,  condensed  translation.    600  w.     (In  Journal 

of  the  Iron  and  Steel  Institute,  v.  57,  p.  427.) 

Microscopic  examination  of  badly  corroded  boiler  tubes. 

Christie,  William  Wallace. 

Corrosion,  35  p.  111.  1906.  (In  his  Boiler-waters, 
p.  68.) 

Treats  rather  fully  the  corrosion  of  boilers,  the  action  of  dif- 
ferent feed-waters  and  the  dangers  of  pitting. 

Churchill,  W.  W. 

Preservation  of  surface  condenser  tubes  in  plants 
using  salt  or  contaminated  water  circulation.  3,000  w. 
1906.  (In  Science,  v.  47,  p.  405.) 

The  same.    (In  Power,  v.  26,  p.  598.) 

Paper  before  the  American  Associatipn  for  the  Advancement  of 
Science. 

Considers  the  prevention  of  electrolytic  corrosion.  Author  pre- 
sents Oliver  J.  Lodge's  views  on  electrolytic  condition  and  Faraday's 
laws  of  electrolysis  as  a  basis  for  his  views. 

Ford,  John  D. 

Corrosion  of  boiler  tubes.  5,200  w.  111.  1904.  (In 
Journal  of  the  American  Society  of  Naval  Engineers, 
v.  16,  p.  529.) 

The  same,  condensed-  1,000  w.  (In  Iron  and  Steel 
Magazine,  v.  10,  p.  349.) 

Extensive  experiments  made  for  the  United  States  Navy  De- 
partment at  the  laboratory  of  the  National  Tube  Co.,  McKeesport. 
to  determine  relative  corrodibility  of  lap-welded  Bessemer  steel,  lap- 
welded  iron,  seamless  cold-drawn  steel  and  seamless  hot-drawn  steel 
boiler  tubes. 

Fremont,  Ch.,  &  Osmond,  F. 

Les  sillons  de  corrosion  dans  les  toles  de  chaudieres 
a  vapeur.  4,200  w.  111.  1905.  (In  Revue  de  metal- 
lurgie,  v.  2,  p.  75.) 

Investigation  of  cause  of  lines  of  corrosion  in  boiler  plates. 

Gesellschaft  fur  Hochdruck-Rohrleitungen. 

Wasserbeschaffenheit  und  korrosionen.  4,000  w. 
111.  1909.  (In  its  Rohrleitungen,  p.  127.) 

Considers  action  of  water  on  iron,  especially  of  boiler-waters, 
and  methods  of  protection. 

Gibbons,  W.  H. 

Physical  reasons  for  rapid  corrosion  of  steel  boiler- 
tubes.  800  w.  111.  1895.  (In  American  Engineer 
and  Railroad  Journal,  v.  69,  p.  157.) 

Considers  difference  in  corrodibility  of  tubes  made  from  the 
"top"  and  the  "bottom"  of  an  ingot,  with  its  application  to  the 
relative  corrosion  of  steel  and  charcoal  iron. 


122  BIBLIOGRAPHY 

Kirtley,  William. 

On  the  corrosion  of  locomotive  boilers  and  the 
means  of  prevention.  8,800  w.  111.  1866.  (In  Pro- 
ceedings of  the  Institution  of  Mechanical  Engineers,  v. 
17,  p.  56.) 

Considers  corrosion  due  both  to  chemical  action  of  water  and 
mechanical  action  of  strain.  The  trouble  may  be  obviated  by  re- 
moving one  of  these  causes,  i.  e.,  by  proper  boiler  design,  eliminat- 
ing springing  at  joints,  etc. 

La  Coux,  H.  de. 

Eaux  corrosives  et  incrusto-corrosives  dans  les 
generateurs  de  vapeitr.  14.500  w.  1899.  (In  Le  Genie 
Civil,  v.  36,  p.  117,  139.  149.) 

Substances  causing  corrosion  and  means  of  prevention. 

McBride,  James. 

Corrosion  of  steam  drums.  8,000  w.  111.  1891, 
1894.  (In  Transactions  of  the  American  Society  of 
Mechanical  Engineers,  v.  12,  p.  518;  v.  15,  p.  1087.) 

Includes  lengthy  discussion. 

Norris,  W.  J. 

Corrosion  in  steam  boilers.  5,000  w.  1882.  (In 
Transactions  of  the  Institution  of  Naval  Architects,  v. 
23,  p.  151.) 

Disagrees  with  theories  of  galvanic  action;  production  of  hydro- 
chloric acid  in  boiler  by  decomposition  of  water;  action  of  fatty 
acids  produced  by  decomposition  of  lubricants,  etc.  Ascribes  all 
boiler  corrosion  to  simple  oxidation  by  presence  in  water  of  free 
oxygen  derived  from  the  air. 

Palmer,  J.  Edward- 

Corrosion  of  steel  boiler  tubes  on  vessels  fitted  with 
turbine  engines.  1,000  w.  1907.  (In  Journal  of  the 
American  Society  of  Naval  Engineers,  v.  19,  p.  54.) 

The  same.     (In  Engineering  News,  v.  57,  p.  426.) 

Corrosion  caused  by  copper  deposits  in  the  tubes,  carried  over  by 
the  steam  from  the  bronze  turbine  blades. 

Paul,  James  Hugh. 

Corrosion  in  steam  boilers.  20  p.  111.  1891.  (In 
Transactions  of  the  Society  of  Engineers,  v.  31,  p.  147.) 

Chemical  properties  of  iron;  manufacture  of  boiler  plates;  cor- 
rosive natural  waters;  artesian  well  waters;  corrosion  in  marine 
boilers;  action  of  zinc. 

Discussion. 

Rinne,  H. 

Kesselmaterial  und  kesselkorrosionen.  5,000  w.  Dr. 
1904.  (In  Stahl  und  Eisen,  v.  24,  pt.  1,  p.  82.) 

Considers  the  corrosion  of  boiler  tubes  of  different  qualities  of 
iron  and  the  influence  of  other  conditions. 


BIBLIOGRAPHY  123 

Worthington,  Walter  F. 

Corrosion  of  boiler  tubes  in  the  United  States 
Navy.  5,000  w.  PI.  1900.  (In  Journal  of  the  American 
Society  of  Naval  Engineers,  v.  12,  p.  589.) 

Causes  of  corrosion  are  discussed,  especially  from  the  action  of 
the  different  impurities  in  feed-water. 

STRUCTURAL   WORK. 

Kent,  William. 

Rapid  corrosion  of  iron  in  railway  bridges.  2,000 
w.  1875.  (In  Journal  of  the  Franklin  Institute,  v.  99, 
p.  437.) 

Considers  sulphurous  acid  one  of  the  most  active  corrosive 
agents. 

Marriott,  William. 

Strengthening  and  maintaining  of  early  iron  bridges. 
10  p.  1905.  (In  Minutes  of  Proceedings  of  the  Insti- 
tution of  Civil  Engineers,  v.  162,  p.  213.) 

Discussion,  47  p. 

Maintains  that  no  iron  bridge  rusts  as  rapidly  as  new  steel 
bridges,  probably  due  to  want  of  homogeneity  or  to  segregation  in 
the  steel. 

Protecting  low  overhead  structures  from  gases  and 
blasts  of  locomotives.  1,600  w.  1904.  ( In  Engineering 
News,  v.  52.  p.  371.) 

Report  of  a  committee,   presenting  opinions  from  many   sources. 

Removal  of  a  steel  frame  building.  800  w.  1903.  (In 
Engineering  News,  v.  49.  p.  113-) 

Good  condition  of  steel  in  Pabst  Hotel,  New  York  City,  five 
years  after  erection. 

Snow,  J.  P. 

Corrosion  of  structural  steel  as  affected  by  its 
chemical  composition.  500  w.  1906.  (In  Proceedings 
of  the  American  Society  for  Testing  Materials,  v.  6, 
p.  148.) 

Suggests  investigation  of  part  played  by  manganese  and  phos- 
phorus. 

WIRE. 

Cushman,  Allerton  S. 

Corrosion  of  fence  wire.  31  p.  1905.  (In  United 
States — Department  of  Agriculture.  Farmers'  Bulletin, 
No.  239.) 

The  same,  condensed.  3,000  w.  (In  Iron  Age,  v.  77, 
p.  207.) 

Investigation  undertaken  for  the  mutual  advantage  of  con- 
sumer and  manufacturer.  Claims  that  the  uneven  distribution  of 
manganese  causes  part  of  the  trouble,  owing  to  electrolytic  action. 


124  BIBLIOGRAPHY 

Rudeloff,  M. 

Untersuchungen  iiber  die  widerstandsfahigkeit  von 
seildrahten  gegen  rosten.  4,000  w.  111.  1900.  (In 
Mitteilungen  aus  den  Koniglichen  Technischen  Ver- 
suchsanstalten,  v.  18,  p.  107.) 

Results  of  many  tests  on  the  resistance  of  wire  to  corrosion. 
Numerous  tables  and  diagrams. 

CONCRETE    REINFORCEMENT. 
Breuille. 

Experiences  sur  le  ciment  arme-  4,500  w.  Dr. 
1902.  (In  Annales  des  ponts  et  chaussees,  memoires, 
ser.  8,  v.  3,  icr  trimestre,  p.  181.) 

The  same,  condensed.  200  w.  (In  Transactions  of 
the  American  Society  of  Civil  Engineers,  v.  51,  p.  124.) 

The  same,  condensed-  100  w.  (In  Taylor  &  Thomp- 
son's Treatise  on  concrete,  plain  and  reinforced,  p. 
430.) 

Argues  against  the  belief  that  cement  does  not  attack  iron. 
Chemical  union  takes  place  between  metal  and  cement,  forming 
silicate  of  iron,  soluble  in  water,  and  unless  special  care  is  taken 
in  waterproofing  the  concrete  this  salt  is  dissolved  and  corrosion 
takes  place. 

Cement  paste  for  protecting  steel.  250  w.  1908.  (In 
Mining  and  Scientific  Press,  v.  97,  p.  744.) 

Successful  coating  used  by  the  Pennsylvania  Railroad,  said  to 
be  cheap  and  durable. 

Corrosion  of  reinforcing  metal  in  cinder-concrete 
floors.  2,200  w.  1906.  (In  Engineering  News,  v.  56, 
p.  458.) 

Contains  report  in  full  of  a  committee  to  the  Structural  Asso- 
ciation of  San  Francisco,  recommending  that  the  building  laws  be 
so  amended  as  to  exclude  cinder  concrete  from  use  in  floor  slabs. 

See  also  editorial,   p.   461. 

Experiment  to  indicate  whether  iron  rusts  when  im- 
bedded in  concrete.  150  w.  1904.  (In  Report  of  the 
Boston  Transit  Commission,  v.  10,  appendix  F,  p.  80.) 

Two-year  tests  give   excellent  results. 

Experiment  to  indicate  whether  steel  imperfectly 
cleaned  is  preserved  from  further  rusting  by  imbed- 
ding the  same  in  concrete.  200  w.  1904.  (In  Report 
of  the  Boston  Transit  Commission,  v.  10,  appendix 
F  2.Tp.  81.) 

No  apparent  increase  of  rust  in  two   years. 

Fox,  William  H. 

Corrosion  of  steel  in  reinforced  cinder-concrete. 
1,600  w.  Dr.  1907.  (In  Engineering  News,  v.  57,  p.  569.) 

Records  experiments  in  which  reinforced  cinder  concrete  was 
exposed  to  steam  and  to  water  for  about  40  days.  Results  showed 
unmistakable  signs  of  corrosion. 


BIBLIOGRAPHY  125 

Himmelwright,  A.  L.  A. 

Corrosion  of  steel  in  cinder  concrete.  1,200  w. 
1907.  (In  Iron  Age,  v.  79,  p.  141.) 

Believes  that  cinder  concrete  should  not  be  condemned  and 
that  the  corrosion  observed  in  San  Francisco  took  place  during 
construction.. 

Hinrichsen,  F.  Willy. 

Zur  kenntnis  des  einflusses  von  koksasche  auf  den 
rostangriff  von  eisen.  1,400  w.  1907.  (In  Mitteilungen 
aus  dem  Koniglichen  Materialpriifungsamt,  v.  25,  p. 
321.) 

Found  that  the  sulphur  in  coke  ashes  has  very  little  action  on 
iron  enclosed  in  cement  and  ashes. 

Immunity  from  rusting  of  reinforcing  steel  in  concrete. 
900  w.  111.  1908.  (In  Engineering  News,  v.  59,  p. 
524.) 

Results  of  tests  at  the  Prussian,  Royal  Testing  Institution, 
showing  that  ordinary  tension  cracks  do  not  allow  corroding  influ- 
ences of  the  atmosphere  to  affect  the  steel. 

Knudson,  Adolphus  A. 

Electrolytic  corrosion  of  iron  and  steel  in  concrete. 
3,200  w.  Diag.  dr.  ill.  1907.  (In  Transactions  of  the 
American  "Institute  of  Electrical  Engineers,  v.  26,  pt. 
1,  p.  231.) 

Discussion,  p.  264.      16,000  w.     Diag.  dr. 

The  same,  zvithout  discussion.  (In  Electrician,  Lon- 
don, v.  59,  p.  213.) 

"In  no  sense  can  concrete  be  considered  an  insulator,  and 
.  .  .  it  is  from  all  appearances  just  as  good  an  electrolyte  as  any 
of  the  soils  found  in  the  earth." 

Langsdorf,  A.  S. 

Electrolysis  of  reinforced  concrete.  1,200  w.  Diag. 
dr.  ill.  1909.  (In  Journal  of  the  Association  of  Engi- 
neering Societies,  v.  42,  p.  69.) 

The  same.  (In  Engineering-Contracting,  v.  31,  p. 
327.) 

In  general  an  amplification  of  earlier  experiments  of  Knudson, 
confirming  his  results. 

Lidy. 

Experiences  sur  1'alteration  des  ciments  armes  par 
1'eau  de  mer.  3,000  w.  1899.  (In  Annales  des  ponts  et 
chaussees,  memoires,  ser.  7,  v.  18,  4e  trimestre,  p.  229.) 

Results  of  experiments  indicate  that  cement  is  not  impermeable 
to  salt  water  and  that  in  time  the  action  of  the  water  will  be 
destructive. 

Matthews,  Ernest  R. 

Corrosion    of    steel    reinforcement    in    concrete.      500 


126  BIBLIOGRAPHY 

w.     1909-     (In  Iron  and  Coal  Trades  Review,  v.  78,  p. 

544.) 

The  same.      (In   Mechanical  Engineer,  v.  3,  p.  441.) 

Abstract  of   paper  before  the   Society  of  Engineers. 
Conclusions    are    that    concrete,    properly    mixed,     gives    almost 
/perfect  protection  to  steel,  with  no  need  for  a  cement  coating. 

•^Newberry,  Spencer  B. 

Chemistry  of  the  protection  of  steel  against  rust 
and  fire  by  concrete.  1,700  w.  1902.  (In  Scientific 
American  Supplement,  v-  54,  p.  22335.) 

The  same.     1,000  w.     (In  Engineering  News,  v.  47, 
p.  335.) 
Nicholas,  U.  James. 

Tests  on  the  effect  of  electric  current  on  concrete. 
3,200  w.  111.  1908.  (In  Engineering  News,  v.  60,  p. 
710.) 

Shows  that  electrolytic  corrosion  of  reinforcing  steel  takes 
place  at  that  anode,  and  that  under  certain  conditions  concrete  and 
cement  are  in  no  sense  insulators. 

Norton,  Charles  L. 

Corrosion  of  steel  frames  of  building.  1,500  w. 
1902.  (In  Iron  Age,  v.  70,  Nov.  6,  p.  7.) 

Report  of  the  Insurance  Engineering  Experiment  Station  of 
the  Associated  Factory  Mutual  Fire  Insurance  Companies,  Boston. 

Tests  to  determine  the  protection  afforded  to  steel 
by  Portland  cement  concrete.  1,700  w.  111.  1902.  (In 
Engineering  News,  v.  48,  p.  333.) 

Indicate  that  neat  Portland  cement  is  a  good  preventive  of 
corrosion  and  that  corrosion  in  cinder  concrete  is  due  to  rust  in  the 
cinders  and  not  to  the  sulphur. 

Corrosion  of  the  steel  frames  of  buildings.  1,800 
w.  111.  1902.  (In  Technology  Quarterly,  v.  15,  p. 
343.) 

Tests  showing  that  concrete  to  be  effective  in  preventing  rust 
must  be  dense,  without  voids  or  cracks,  mixed  and  applied  quite 
fresh  to  clean  metal. 

Protection  of  steel  from  corrosion.  1,600  w.  1904. 
(In  Engineering  News,  v.  51,  p.  29.) 

Laboratory  experiments,  tending  to  show  that  concrete  properly 
applied  is  an  almost  perfect  preservative. 

Preservation  of  iron  in  concrete.     700  w.     1903.      (In 
Engineering  Record,  v.  47,  p.  554.) 

Observations  on  condition  of  iron  embedded  in  concrete  since 
1890. 

Schaub,  J.  W. 

Some  phenomena  of  the  adhesion  of  steel  and  con- 
crete. 1,400  w.  1904.  (In  Engineering  News,  v.  51, 
p.  561.) 

Points  out  that  a  chemical  union  takes  place  between  the  iron 
and  the  cement  and  that  this  union  is  dissolved  in  water. 


BIBLIOGRAPHY  127 

Tests  on  rusting  of  steel  rods  embedded  in  concrete. 
600  w.     1908.     (In  Engineering  News,  v.  59,  p.  525.) 
Tests  made  by  J.  M.  Braxton,  United  States  engineer. 

Thwaite,  Benjamin  Howard. 

Preservation  of  iron  and  steel.  1.90G  w.  1906.  (In 
Iron  and  Steel  Magazine,  v.  11,  p.  411.) 

From  "Concrete  and  Constructional  Engineering." 
Calls  attention   to  excellent  results   obtained  by   use   of   cement 
and  concrete  coverings. 

Toch,  Maximilian. 

Permanent  protection  of  iron  and  steel.  2,300  w. 
111.  1903.  (In  Journal  of  the  American  Chemical 
Society,  v.  25,  p.  761.) 

Considers  that  metal  work,  coated  with  cement  paint,  then  with 
hydrocarbon  insulating  paint,  will  be  perfectly  protected  when 
embedded  in  masonry. 

Electrolytic  corrosion  of  structural  steel.  1,800  w. 
1906.  (In  Transactions  of  the  American  Electrochem- 
ical Society,  v-  9,  p.  77.) 

The  same,  zvithout  discussion.  1,000  w.  (In  Chemical 
Engineer,  v.  4,  p.  125.) 

The  same,  condensed.  1,500  w.  (In  Electrochemical 
and  Metallurgical  Industry,  v.  4,  p.  215-) 

Denies  that  concrete  is  a  complete  protector  against  corrosion, 
and  cites  experiments  showing  that  in  structural  steel  embedded  in 
concrete  rapid  corrosion  takes  place  at  the  anode  while  the  cathode 
is  protected. 

Electrolytic  corrosion  of  structural  steel.  1,300  w. 
111.  1906.  (In  Proceedings  of  the  American  Society 
for  Testing  Materials,  v.  6,  p.  150.) 

Tests  of  steel  embedded  in  various  mixtures  of  concrete  show 
that  the  concrete  is  no  protection  unless  the  steel  is  otherwise 
insulated. 


INDEX 


PAGE 

Absorption  of  gases  (see:  Occlusion). 

Acid  and  basic  steels,  comparative  corrosion  of.  .58,  87 

Acid    tanks,    corrosion    of 59 

Acid   tests    for    corrosion 22,  55,  57,  87 

Acids  (see:  Chromic,  Hydrofluoric,  Sulfuric). 

Acids,  solubility  of  iron  in 51,  56,  57 

Acidulated  water,  corrosion  in 66 

Air   (London),  composition  of 60 

Air,   corrosion   in 7,  62 

Alcohol,    corrosion    in 62 

Alternate  wetting  and  drying 63 

Aluminium  in  iron,  influence  of .» 30 

Ammonia  in  rusting 5,  88 

Ammonia  in  the  air 60,  62 

Analyses   of  rust 4, 66 

Annealing     41 

Anode,   corrosion   of 17,  98 

Arsenic   to   inhibit  rusting 96 

Ashes,   corrosion   in   damp 75 

Atmospheric    pollution     60 

Austenite   53 

B 

Basic  and  acid  steels,  comparative  corrosion  of..  58,  87 

Bessemer   and  mild   steel   wire   compared 78 

Bichromates  of  potassium  and  of  sodium. ..  .36,  96,  97, 

98,99 

Bilge-water,   rusting   in 69 

Blowholes    42 

Boats,   etc.,   made   of   reinforced   concrete 93 

Boiler  compounds   77 

Boiler   sheets,    corrosion   of 77 

Bower  Barffing 81 

Brackish  water,  rusting  in 64 

129 


PAGE 

Brass   in   contact   with   iron 68 

Bridges,  rusting  of 63 

Brine,   tests    in 57,  76 

Bromides,   effect  of 65 

Bronze  in  contact  with  iron 68 

Buried   pipe,    corrosion    of 74 

c 

Carbides    of    iron ..38,52,53,54,55,82 

Carbon  as  a  mechanical  protection 82 

Carbon,    influence    of    30,31,55,81,82 

Carbon    in    steel    and    iron 38,59 

Carbonates,    protective    effect    of 91 

Carbonate  of  iron  (see:  Ferrous  carbonate). 

Carbonating    processes    82 

Carbonic-acid   theory    9, 91 

Carbonic  acid  (see:  Carbonic  dioxide). 

Carbonic    dioxide,    action    of 63,  66,  88,  91 

Carbonic  dioxide  in  water   9 

Carbonic  oxide,  occluded   43 

Care  of  steel  structures 2,  44 

Carelessness  of  manufacture 43 

Cast    iron,    corrosion    of 50,  65,  82 

Cast  iron,  hard  and  soft 42 

Cement    in    ships 69,  93 

Cement,  iron  and  steel  embedded  in 89 

Cement,  neat    ,90,  91,  92 

Cement  paint 90,  92 

Cement,  Portland   90,  93 

Cement,  removal   of  rust  by 90 

Cement,  slag    93 

Cementite    38,  52,  53,  54,  82 

Chain,  rust  from  4 

Charcoal-iron    .• 49,  56,  75,  83 

Chilled  iron  38,  40 

Chilling,   effect  of 47 

Chlorides,    effect   of 65 

130 


PAGE 

Chlorine,    effect    of 61,  62 

Chromic  acid  to  inhibit  rusting 97 

Chromium,    influence    of 81 

Chromium   steel    56 

Cinder  (see:  Slag) 

Cinder  .concrete  92 

Coal-gas,  effect  of 82 

Coal  in  ships,  effect  of 69 

Cold-shortness 83 

Color  of  rust   3, 54 

Combined  water  in  rust  3,  4,  5 

Combustion   gases,   effect   of 60 

Comparative  corrosion  of  acid  and  basic  steels.  .58, 87 

Comparative  corrosion  of  iron  and  steel 49,66,67 

68,  73,  83 

Composition   of    rust 3,  4,  66 

Compressed  steel,   corrodibility  of 42 

Concrete  boats,  etc 93 

Concrete,  cinder   92 

Concrete,  "iron  and   steel  embedded  in. 89 

Condensation   of  moisture 8,  15 

Conditions,  influence  of  modern 60 

Conductivity    (electrical)    and   rusting 29,  43,  46,  85 

Cones  and  craters  in  rusting 21 

Contact  effects  (see:  Galvanic  action). 

Contact  of  brass  or  bronze  with  iron 68 

Contact  of  copper  or  tin  with  iron 68 

Contact  of  cement  with  iron 95 

Contact  of  iron  with  rust 71 

Contact  of  iron  with  steel 66,  67,  68 

Contact  of  iron  with  wood 68 

Copper  in   contact   with    iron 68 

Corrosion   of   iron   and  steel,   comparative.  ..  .49,  66,  67, 

68,  73,  80 

Corrosion  tests    1 1,  12,  19,  23,  80 

Craters  and  cones  in  rusting 21 

131 


PAGE 

Crystalline  rust   5 

Crystalline  structure  of  iron  and  steel 40 

Current  (see:  Electric  current). 

D 

Decay  of  iron  and  steel 1,  81,  94,  100 

Decomposition  by  salt   water 66 

Delta  metal 68 

Density  of  iron   62 

Depolarizer,   rust  as   a 8 

Depolarizers 36,  37,  98 

Depth  of  corrosion  (see  also:  Pitting) 7 

Difference  between  iron  and  steel 38 

Diffusion  through   pores    32 

Disintegration  of  metals    5 

Dissociation  by  diffusion 32 

Dissociation   of  hydrogen 32 

Double-layer   theory    33,  35 

Dust,  effect  of   64 

Dusts,  oxidation  of    32 

E 

Electric   conductivity  and   rusting 29,  43,  46,  85 

Electric   current,   influence    of 88 

Electric    furnace,    iron    from 62 

Electric  inoxidation   17 

Electric  pickling   98 

Electric  potential  and  rusting 29 

Electric  resistance   and   rusting 29,  43,  46,  85 

Electrolysis     60 

Electrolytic  theory 14,  23 

Eutectics    ' 39,  81,  83 

Exfoliation    74 

F 

Fence   wire,   corrosion   of 78 

Feroxyl  reagent  tests 19,  23 

Ferric  oxide   4 

132 


PAGE 

Ferric  sesquioxide    

Ferrite    38,  52,  54,  82 

Ferrocyanide  of  potassium  to  inhibit  rusting 96 

Ferro-manganese,  corrosion  of 87 

Ferrous  carbonate  as  rust  promoter 11 

Ferrous   carbonate   in   rust 3,     4 

Ferrous  carbonate,  oxidation  of 10,  11 

Ferrous  oxide 4 

Ferrous  sulfate,  tests  in 57 

Fibrous  iron 40 

Formation  of  rust 6,  8,  10,  14,  15,  25 

Formulae  of  rusting  9,  13,  18 

Fracture  of  iron  and  steel 40 

Fresh  water,  rusting  in 7,  63 

G    , 

Galvanic    action     1 7,  22,  34,  36,  47,  52,  66,  68, 

81,83,84,95,96,97,98 

Galvanic  action  of  mill-scale 6 

Galvanic  action  of  rust  8 

Galvanic  action  of  slag 6 

Galvanic  solubility    14,  34 

Galvanized  pipe,  corrodibility  of 74 

Galvanized    work,    bichromating    of 100 

Gas-holders,  corrosion  of 82 

Gases  absorbed    (see:   Gases,   occluded). 

Gases  dissolved  in  water 9, 10 

Gases    (occluded),    effect    of 17,27,43,84,95,98 

Gases    (occluded),   removal    of 31,  99 

Gases  (waste)  effect  of 60 

Graphite  in  iron,  influence  of 38,  83 

Growth  of  rust  6,  8,  20 

Gun-metal  in  contact  with  iron 68 

Guns    left   in   sea-water 66 

H 

Hardening  by  gas  occlusion 28,  29,  31 

Hardening,  effect  of  47,  53 

133 


PAGE 

Hardening  of  steel 38 

Hardness    of    iron 28,  82 

Heat   treatment    39,  40,  42,  54,  61 

Heterogeneous   metal    (see:   Homogeneity). 

Homogeneity    21,  43,  61,  64,  65,  79,  81,  86 

Hoops  embedded  in  cement 90 

Hot  iron,  oxidation  of 26 

Hot  water  pipes,  corrosion  of 74 

Hydration  of  rust 3,  4,  5 

Hydrofluoric  acid  and  iron 51 

Hydrogen,  dissociation  of 32 

Hydrogen  in  corrosion,  function  of.  .14,  15,  16,  18,  24,  25 

27,  30,  36,  64,  85, 98,  99 

Hydrogen,    occluded    (see    also:    Hydrogen,    func- 
tion of)   17,  27,  43 

Hydrogen  peroxide,  rusting  in 13 

Hydrogen  peroxide  theory 13 

Hydrogen,   removal    (see   also:   Oxygen,  functions 

of)    36 

Hygroscopic  rust   7 

I 

Impurities  in  air   60,  62 

Impurities   in  iron 38 

Impurities   in    rivers 63 

Impurities    in    water 15,  63,  64 

Impurities,    influence    of 21,24,25,27,59,61,81 

Impurities,  removal  of 86 

Indicators  (see:  Feroxyl). 

Indicators,  hydrogen  and  oxygen  as 98 

Influence  of  modern  conditions 60 

Ingot-iron    56 

Inhibition    of   rusting 34,  36,  95 

Inoxidation,  electric  (see  also:  Bower-Barffing)  . . .       17 
Iron    (see:    Cast,    Charcoal,    Chilled,    Electrolytic, 
Malleable,  Wrought). 

134 


PAGE 

Iron  and  steel,  comparative  corrosion  of 49,66,67, 

68,  73,  80 

Iron   and  steel,  contact  between 66,67,68 

Iron  and  steel,  difference  between 38 

Iron  and  wood,  contact  between 68 

Iron,  'hardness    of 28,  82 

Iron  in  solution 10,  14,  15,  18,  21,  22,  37 

L 

Lead  in  contact  with  iron 68 

London  air,  composition  of 60 

M 

Malleable  iron,  occluded  gases  in 31 

Manganese,  influence  of 4,  30,  31,  39,  58, 

79, 81,  84, 85,  86 

Manganese   dioxide    paints    86 

Martensite    39 

Masses,  metal   in 42,  61 

Mechanical  treatment 41,  42,  43,  45,  54 

Metillures    83 

Microscopical    examination    of   iron 21,  97 

Mild  steel 38 

Mild  steel  and  Bessemer  wire  compared 78 

Mill-scale   (see  also:  Oxide  of  iron,  black) 4,70,81 

Modern   conditions,   influence    of 60 

Moisture  must  condense  8,  15 

Muntz   metal    69 

N 

Nature  of  rust  5,  7,  8 

Neat  cement  as  protection  against  corrosion.  .90,  92,  93 

Nickel   in    contact  with   iron 69 

Nickel,  influence  of 81 

Nickel-steel,  corrodibility  of 56,  58 

Nitric  acid  to   inhibit   rusting 96 

Nitrogen,  occluded   43 

135 


o 

PAQE 

Occluded  gases,  removal  of 31 

Occlusion    of    gases 17,27,43,84,95,98 

Oils,  corrosive  action  of 77 

Organic   matter,    corrosive    action   of 63,65,69 

Osmosis '. 18,  32 

Overheated  metal  (see  also:  Heat  treatment) 55 

Oxidation  of  dusts,  spontaneous 32 

Oxide,   black  or  magnetic 3,17,26,81,86 

Oxide,  ferric 4 

Oxide,  ferrous    4 

Oxide  (sesqui-)   of  iron 3,     8 

Oxides  of  metals,  contact   effect  of 85,  90 

Oxidizing  agents  as  rust  inhibitors 100 

Oxygen  in  corrosion,  function   of 8,  15,  36,  62,  63 

Oxygen,  inhibition  of  rusting  by 96 

P 

Paint  (see:  Cement,  Graphite,  Manganese  dioxide, 
Red-lead,  Venetian-red). 

Painted  iron 79,  86 

Panama,   chain   from 5 

Passive    conditions    of   iron 86,95,98,99,100 

Pearlite    38,  53,  54 

Peroxide   (see:  Hydrogen  peroxide). 
Phenolphthalein  (see:  Feroxyl). 

Phosphorus  in  iron    39 

Phosphorus,    influence    of 83 

Pickling  of  iron 51,  98 

Pickling,  hydrogen  due  to 28,  29,  31 

Pig-iron,  manganiferons    31 

Pipe,   corrosion    of    42,  57,  66,  73,  82 

Pipe  dissolved  by  acids 51 

Pitting    6,  20,  21,  53,  73,  74,  75,  77,  81 

Plates  of  ships    67 

Polarization    36,  37,  98 

Pollution  of  the  atmosphere 60 

136 


PAGE 

Pollution    of    rivers 63 

Porosity  of   metals 43 

Porous  metal,  oxidation  of 33,  42 

Portland  cement  and  iron 90,  93 

Potential  differences   (see  also:  Galvanic  action. .  .7,  14, 

16,19,20,22,25,46,53,99 

Potential   (electrical)   and  rusting  (see  also:   Con- 
ductivity)          29 

Potassium    bichromate   to    inhibit   rusting 36,96 

97,  98,  99 

Potassium  ferrocyanide  to  inhibit  rusting 96 

Prejudice  against    steel    60, 61 

Pressure  of  solution 16,  34 

Prevention  of  corrosion   (see:  Inhibition). 

Progressive  nature  of  corrosion 3 

Puddling,  effects  of 1 61 

Pure  metals,  effects  of  reagents  on 53 

R 

Rails,  corrosion  of 70,  85 

Rails,   rust   from 4 

Railway  bridges,  corrosion  of 62 

Rain  water,  rusting  in 64 

Rapid   oxidation    

Rate  of  corrosion 3,  7,  50 

Red-lead  paint    83 

Reinforced  concrete    (see:   Concrete). 

Relation  of  structure  to  corrosion 42 

Relative  (see:  Comparative). 

Removal  of  gaseous  hydrogen 36 

Removal    of   impurities    ' 86 

Removal  of  occluded  gases 31 

Removal  of  rust  by  cement 90 

Residual  gas  in  water 9,  10 

Resistance  (see:  Conductivity). 

River  water,  corrosion  in 75 

Rivers,  impurities  in 63 

137 


PAGE 

Rivet-rod,  rust  from 4 

Rolled  material,   corrosion   of 78,  79 

Rough   surface    of  iron 79 

Rust,  color  of 3,  53 

Rust,   composition   of 3,  4,  66 

Rust,  contact  effect  of 71 

Rust,  formation  of 6,  8,  10,  14,  15,  25 

Rust  formed  under  water 3 

Rust  formulae  9,  13,  18 

Rust  from  chain,  analysis  of 4 

Rust  from  rails,  analysis  of 4 

Rust  from  rivet-rod,  analysis  of 4 

Rust  from  sheets,  analysis  of 4 

Rust  from  tanks,  analysis  of 4 

Rust,  growth  of 6,    8 

Rust,  nature  of 5,  7,  8 

Rust  removal  by  cement 94 

Rust  structure  of 5,  7,  8 

Rust  theories  8,  9,  13,  14,  23,  91 

Rust,  tubercular 6 

s 

Salt-water,   corrosion    in 56,  62,  64,  65,  66,  67,  69,  75,  76 

Salts  of  metals,  contact  effect  of 85,86 

Saturated   steel    53,  59 

Scale,  galvanic  action  of  6 

Sea-water  (see:  Salt-water). 

Segregation 44 

Service  tests   . -. 57,  73,  76,  79 

Sesqui-oxide   of  iron 3 

Sewage,   corrosive   action   of 65 

Sheets,    corrosion    of 79' 

Sheets   (boiler),  corrosion  of 77 

Sheets,  rust  from   4 

Shiny  rust  3 

Ship-plates,  corrosion  of 67 

Ships,  cement  used  for  and  in 69,  93 

138 


PAGE 

Shock,  effect  of 40 

Shortness   in   steel 41,  74,  83 

Silicon  in  iron 30,  31,  39 

Silicon,    influence    of 83,  84,  85 

Silicon  steel,  corrodibility  of  high 56 

Skelp  (see  also :  Pipe) 73 

Skin  on  metals 50,  71,  78 

Slag,  influence  of 6,  50,  51,  55,  59, 61,  79 

Slag  cement   93 

Snow,  analysis  of  London 60 

Sodium  bichromate  to  inhibit  rusting 36,  99 

Sodium  nitrite  to  inhibit  rusting 96 

Solubility,   galvanic    14,  15 

Solubility,  nature  of    14,  15 

Solution  of  iron  in  acids .' 22,  51,  55,  57 

Solution  of  iron  in  water 10,  14,  15,  18,  21,  22,  37 

Solution   pressure    or   tension 16,  33 

Soot    62 

Specific    gravity    of   iron 62 

Spellerizing    75 

Spiegeleisen,  corrodibility  of 82 

Spontaneous  oxidation   32 

Spreading    of    rust 6,  8,  20 

Steam-pipe,    corrosion    of 74 

Steel  and  iron,  comparative  corrosion  of 49,  66,  67, 

68,  73,  80 

Steel  and   iron,   contact  between .66,67,68 

Steel  and  iron,  difference  between 38 

Steel,   hardening  of    38 

Steel,   high-carbon    81 

Steel,  mild  38 

Steel  structures,  care  of 2 

Strain  and  temperature,  relation  between 46 

Strain  as  affecting  structure 41 

Stress  as  affecting  corrosion 20,  43,  44,  45 

Structure,  improvement  of 75 

139 


PAGE 

Structure  of  iron  and  steel 40 

Structure  of  rust    S,  7,  8 

Structure  as  affecting  corrosion 42,  54 

Sulphur  in  iron 39 

Sulphur,   influence   of 81,  83,  85 

Sulphur  dioxide  in  the  air 62 

Sulphuric  acid  tests   (see:  Tests) 

Sulphuric  acid  in  the   air 62 

Sulphuric  acid  to  inhibit  rusting 96 

Surface  of  iron 82,  97 

Surface    treatment 75,  100 

T 

Tanks,  corrosion  of  acid 59 

Tanks,  rust  from  (analysis)  4 

Temperature  at  which  steel  is  finished   (see  also: 

Heat  treatment)    54,  61 

Temperature  and  strain,  relation  between 46 

Tempered  steel   47,  53 

Tension  of  solution  16,  34 

Tests  for  corrosion   11,  12,  19,  22,  23,  45,  50,  55,  56, 

57,  58,  66,  68,  73,  75,  76,  77,  88 

Tests   (acid)  for  corrosion 22,  55,  56,  87 

Tests  (electrolytic)  for  corrosion 45 

Tests   (service)  for  corrosion 57,  73,  76 

Tests  in  brine   57,  76 

Tests  in  ferrous  sulfate 57 

Tests  in  river  water 75 

Tests  in  salt  water.. 66,68,  75,76 

Texture   (see:   Structure). 

Theories  of  rusting 8,  9,  13,  14,  23,  91 

Theory,  carbonic-acid   9 

Theory,  electrolytic  14,  23 

Theory,  hydrogen  peroxide    13 

Theory  of  the  double-layer 33,  35 

Thin  material,  corrosion  of 79 

Tin  in  contact  with  iron 68 

140 


PAGE 

Tobin  bronze  69 

Tropics,  corrosion  in  the 62 

Tubes  (see:  Pipe). 

Tubercular  corrosion    6 

Tungsten  steel   56 

Tunnels,  air  in  62 

V 

Vacuum   to   destroy   passivity 98 

Vanadium  steel   56 

Venetian-red  paint •  •  . .       86 

Vibration,   effect   of 40,  71 

Voltaic  action  (see:  Galvanic  action). 

w 

Wart-like  rust  6 

Wash-space  in  ships ! 63 

Waste  gases  of  combustion 60 

Watch  spring,  energy  of 47 

Water    (see:    Acidulated,    Bilge,    Brackish,    Brine, 
Hot,  Rain,  Salt,  Well). 

Water  (combined)  in  rust 3,  4,  5 

Water  in  rusting,  function  of 8,  15 

Water,  impurities  in 63,  64 

Water  mains,  rust  in    6 

Welding  of  iron  and  steel  compared 73 

Whitworth   process    31 

Wire,  corrosion  of 78 

Wood  in  contact  with  iron 68 

Wrought  iron,  corrosion  of 50 

z 

Zinc  in  boilers 77 


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